LIGHTWEIGHT BUILDING CONSTRUCTION WITH LOCALLY AVAILABLE MATERIALS
By
Weisheng Hong

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
Civil Engineering―Master of Science
2017

ABSTRACT
LIGHTWEIGHT BUILDING CONSTRUCTION WITH LOCALLY AVAILABLE MATERIALS
By
Weisheng Hong
Aerated slurry-infiltrated chicken mesh was evaluated as a lightweight and structurally resilient
material for building construction. Aerated slurry with relatively low structural qualities was shown
to perform favorably when used as a matrix with chicken mesh reinforcement in structural
applications. The high specific surface area of chicken mesh and the close spacing of its wires (when
used at 2-4% volume fraction) effectively enhance the mechanical performance and dimensional
stability of the aerated slurry. The chicken mesh structural behavior also benefits significantly from
embedment in the aerated slurry which mitigates the reorientation tendency of the chicken mesh
wires under tension. This effect enables mobilization of the tensile load-carrying capacity of the
wires in chicken mesh at structurally viable deformations.
A comprehensive experimental program was undertaken at materials and structures levels in order
to develop aerated slurry-infiltrated chicken mesh materials and structural systems with a desired
balance of strength, ductility and hysteretic energy dissipation capacity. The bulk density of the
aerated slurry and the chicken mesh volume fraction were some key variables in design of the new
(composite) building material. With proper selection of these variables, the synergistic actions of the
aerated slurry and the chicken mesh in the context of the composite material were confirmed.
Empirical models were developed for the mechanical performance of this composite material.
The aerated slurry-infiltrated chicken mesh composite material is amenable to joining via screw and
(to some extent) nail application. An experimental study was conducted in order to evaluate the

effects of screw (or nail) type and geometric attributes as well as the aerated slurry-infiltrated
chicken mesh bulk density and reinforcement condition on the pullout and (unilateral and cyclic)
lateral behavior of screws and nails applied to aerated slurry-infiltrated chicken mesh sheets.
The combination of experimental data produced on structural elements, joints and joined
components were used to design a building structure for efficient and safe performance under
gravity and seismic loads. The full-scale building system is currently under construction for verifying
its structural performance through shaking table tests.

ACKNOWLEDGMENTS

I would like to express my greatest gratitude towards my advisor, Dr. Parviz Soroushian, Professor of
Civil Engineering and Environmental at Michigan State University. With his help, I gained much
valuable knowledge. With his patience, support, encouragement and guidance, I could successfully
complete my dissertation research project and graduate studies. With his support, I learned how to
be a good scientist.
I would also like to appreciate Professor Roozbeh Dargazany and Professor Weiyi Lu for joining my
guidance committee, and providing me with valuable help towards completing my dissertation
research project.
I would like to thank fellow research group members, Areej Almalkawi and Mohammad Al-Orfi for
their support and helpful suggestions. During my research project, they helped me overcome
significant difficulties. I would not have been able to conduct my research project if they had not
helped me with developing the required technical background and skills.
Additionally, I also would like to thank all the faculty members in the department of Civil and
Environmental Engineering Department at Michigan State University, and all my fellow graduate
students. I thank them for their help and support both in my research project and in my graduate
coursework. I met many people during my time at MSU who helped me grow, and were willing to listen
as I worked through both research and life problems.
Finally, I would also like to thank my family for their unconditional love and support
throughout my academic life. Both my mother and father have been constant sources of
encouragement throughout my life.

iv

TABLE OF CONTENTS

LIST OF TABLES .............................................................................................................................................. viii
LIST OF FIGURES .............................................................................................................................................. ix
CHAPTER 1 ....................................................................................................................................................... 1
INTRODUCTION ............................................................................................................................................... 1
1.1.

General ................................................................................................................................................... 1

1.2.

Summary of Research ............................................................................................................................ 1

1.2.1.

Mechanical Properties of Aerated Slurry-Infiltrated Chicken Mesh .............................................. 2

1.2.2.

Screw and Nail Behavior in Aerated Slurry-Infiltrated Chicken Mesh ............................................ 2

1.2.3.

Behavior of a Lightweight Frame Made with Aerated Slurry-Infiltrated Chicken Mesh Under

Cyclic Lateral Loading ..................................................................................................................................... 3
1.2.4.

Structural Evaluation of a Lightweight Building System Made with Locally Available Materials ... 3

1.2.5.

Structural Design of a Lightweight Building System Made with Locally Available Materials ......... 4

1.2.6.

Durability Characteristics of Aerated Slurry-Infiltraetd Chicken Mesh .......................................... 4

CHAPTER 2 ....................................................................................................................................................... 5
MECHANICAL PROPERTIES OF AERATED SLURRY-INFILTRATED CHICKEN MESH ................................................ 5
2.1.

Introduction ........................................................................................................................................... 5

2.2.

Experimental Program ........................................................................................................................... 6

2.2.1.

Materials ........................................................................................................................................ 6

2.2.1.1.

Aerated Slurry ............................................................................................................................................ 6

2.2.1.2.

Chicken Mesh ............................................................................................................................................ 7

2.2.2.

Experimental Methods .................................................................................................................. 7

2.2.2.1.

Tests performed on slurry without chicken mesh reinforcement .............................................................. 8

2.2.2.2.

Tests performed on aerated slurry-infiltrated chicken mesh ..................................................................... 9

2.3.

Test Results and Discussion .................................................................................................................. 11

2.3.1.

Compressive strength and bulk density of aerated slurry ........................................................... 11

2.3.2

Compressive behavior of the aerated slurry-infiltrated chicken mesh ........................................ 13

2.3.3

Tensile behavior of aerated slurry-infiltrated chicken mesh ........................................................ 14

2.3.4.

Flexural performance ................................................................................................................... 17

2.3.5.

Analysis of aerated slurry-infiltrated chicken mesh ..................................................................... 19

CHAPTER 3 ..................................................................................................................................................... 23
SCREW AND NAIL BEHAVIOR IN AERATED SLURRY-INFILTRATED CHICKEN MESH............................................ 23
3.1.

Introduction ......................................................................................................................................... 23

3.2.

Material and Methods ......................................................................................................................... 24

3.2.1

Materials ...................................................................................................................................... 24

3.2.2

Test Methods ............................................................................................................................... 25

3.3.

Test Results and Discussion .................................................................................................................. 28

3.3.1.

Screw or Nail Pullout Behavior in Aerated Slurry-Infiltrated Chicken Mesh ................................ 28

v

3.3.2.

Screw or Nail Lateral Behavior in Aerated Slurry-Infiltrated Chicken Mesh Sheets ..................... 30

3.3.3.

Screws and Nail Cyclic Lateral Behavior in Aerated Slurry-Infiltrated Chicken Mesh Sheets ....... 32

CHAPTER 4 ..................................................................................................................................................... 35
BEHAVIOR OF A LIGHTWEIGHT FRAME MADE WITH AERATED SLURRY-INFILTRATED CHICKEN MESH UNDER
CYCLIC LATERAL LOADING .............................................................................................................................. 35
4.1.

Introduction ......................................................................................................................................... 35

4.2.

Materials and Methods ........................................................................................................................ 36

4.2.1.

Aerated Slurry .............................................................................................................................. 36

4.2.2.

Chicken Mesh............................................................................................................................... 37

4.2.3.

Aerated Slurry-Infiltrated Chicken Mesh ..................................................................................... 37

4.2.4.

Aerated Slurry Infiltrated Chicken Mesh Frame ........................................................................... 38

4.2.5.

Cyclic Testing ................................................................................................................................ 41

4.3.

Test Results and Discussion .................................................................................................................. 44

4.3.1.

Yield load and yield displacement ............................................................................................... 49

4.3.2.

Ductility........................................................................................................................................ 50

CHAPTER 5 ..................................................................................................................................................... 52
STRUCTURAL EVALUATION OF A LIGHTWEIGHT BUILDING SYSTEM MADE WITH LOCALLY AVAILABLE
MATERIALS .................................................................................................................................................... 52
5.1.

Introduction ......................................................................................................................................... 52

5.2.

Experimental Program ......................................................................................................................... 53

5.2.1

Introduction ................................................................................................................................. 53

5.2.2

A Brief Review of the Material Properties of Aerated Slurry-infiltrated Chicken Mesh ............... 53

5.2.3

Aerated Slurry-Infiltrated Chicken Mesh Sheets .......................................................................... 55

5.2.4

Aerated Slurry-Infiltrated Chicken Mesh Beams .......................................................................... 56

5.2.5

Aerated Slurry-Infiltrated Chicken Mesh Columns ....................................................................... 57

5.2.6

Aerated Slurry-Infiltrated Chicken Mesh Subcomponents .......................................................... 58

5.3

Experimental Results ............................................................................................................................ 61

5.3.1

Aerated Slurry-Infiltrated Chicken Mesh Sheets .......................................................................... 61

5.3.2

Aerated Slurry-Infiltrated Chicken Mesh Beams .......................................................................... 63

5.3.3

Aerated Slurry-Infiltrated Chicken Mesh Columns ....................................................................... 66

5.3.4

Aerated Slurry-Infiltrated Chicken Mesh Subcomponents .......................................................... 67

CHAPTER 6 ..................................................................................................................................................... 71
STRUCTURAL DESIGN OF A LIGHTWEIGHT BUILDING SYSTEM MADE WITH LOCALLY AVAILABLE MATERIALS . 71
6.1.

Introduction ......................................................................................................................................... 71

6.2.

Design Loads ........................................................................................................................................ 71

6.2.1

Roof Loads ................................................................................................................................... 71

6.2.2

Floor Loads .................................................................................................................................. 72

6.2.3

Seismic Forces (Base Shear Method) ........................................................................................... 72

6.3.

Structural Analysis and Design of Building Frames .............................................................................. 77

6.3.1

Structural Analysis of Building Frames......................................................................................... 77

6.3.2

Design of Roof Sheets .................................................................................................................. 85

6.3.3

Design of the Floor Sheets as Slabs-on-Grade ............................................................................. 86

vi

6.3.4

Footing Design ............................................................................................................................. 88

6.3.5

Design of Screws .......................................................................................................................... 91

CHAPTER 7 ..................................................................................................................................................... 94
DURABILITY OF AERATED SLURRY-INFILTRATED CHICKEN MESH ..................................................................... 94
7.1.
7.2.

Introduction ................................................................................................................................. 94
Material and Methods ......................................................................................................................... 95

7.2.1.

Repeated Wetting-Drying Cycles ................................................................................................. 95

7.2.2.

Repeated freezing-Thawing Cycles .............................................................................................. 96

7.3.

Test Results and Discussion .................................................................................................................. 97

CHAPTER 8 ................................................................................................................................................... 101
CONCLUSIONS.............................................................................................................................................. 101
8.1.

Mechanical Properties of Aerated Slurry-Infiltrated Chicken Mesh ................................................... 101

8.2.

Screw and Nail Behavior in Aerated Slurry-Infiltrated Chicken Mesh ................................................ 102

8.3.

Behavior of a Lightweight Frame Made with Aerated Slurry-Infiltrated Chicken Mesh Under Cyclic

Lateral Loading ............................................................................................................................................... 104
8.4.

Structural Evaluation of a Lightweight Building System Made with Locally Available Materials ....... 105

8.5.

Structural Design of a Lightweight Building System Made with Locally Available Materials ............. 106

8.6.

Durability Characteristics of Aerated Slurry-Infiltrated Chicken Mesh ............................................... 107

REFERENCES ................................................................................................................................................. 108

vii

LIST OF TABLES

Table 1. The aerated slurry mix proportions. ..................................................................................................9
Table 2. Compressive strength and bulk density of different aerated slurry mixtures (Mix 0 is non-aerated).
......................................................................................................................................................................12
Table 3. A summary presentation of the tensile strength test results for slurry-infiltrated chicken mesh
sheets with different slurry densities and number of chicken mesh layers..................................................17
Table 4. Aerated slurry-infiltrated chicken mesh sheet and beam dimensions, reinforcement and loading
conditions, and test results versus predicted values. ...................................................................................22
Table 5. The displacement cycles used in lateral testing of nails. .................................................................28
Table 6. Summary of the screw and nail pullout test results. .......................................................................30
Table 7. Test protocol for evaluation of the frame performance under cyclic lateral loads .........................43
Table 8. Failure load and displacement at failure of aerated slurry-infiltrated chicken mesh frame versus
alternative lateral load-carrying systems of comparable geometric attributes. ...........................................49
Table 9. The parameters required for calculation of the yield load (and the calculated value of yield load).
......................................................................................................................................................................50
Table 10. The thickness, number of chicken mesh layers, and the volume fraction and cross-section area
fraction of chicken mesh reinforcement. ......................................................................................................56
Table 11. Test protocol for evaluation of the frame performance under cyclic lateral loads .......................61
Table 12. Site soil amplification factor relative to acceleration (short period, firm soil). .............................73
Table 13. Seismic response modifier (R) values for residential construction................................................74
Table 14. Aerated slurry infiltrated chicken mesh sheet and beam dimensions, reinforcement and loading
conditions, and test results versus predicted values. ...................................................................................82
Table 15. Presumptive soil bearing values for different soil types................................................................89
Table 16. Flexural strength test results. ........................................................................................................98

viii

LIST OF FIGURES

Figure 1. Preparation of foamed water by stirring the mixing water incorporating the foaming agent.........6
Figure 2. The chicken mesh used in the experimental program. ....................................................................7
Figure 3. Aerated slurry-infiltrated chicken mesh compression test specimen. ...........................................10
Figure 4. Tension test setup. .........................................................................................................................10
Figure 5. Flexure test setup. ..........................................................................................................................11
Figure 6. Compressive strength and bulk density test results for different aerated slurries. .......................13
Figure 7. A typical compressive stress-deflection behavior of aerated slurry-infiltrated chicken mesh.......14
Figure 8. Tensile load-deflection curves for non-aerated and aerated slurry-infiltrated chicken mesh, and
also for chicken mesh tested alone (without slurry-infiltration). .................................................................16
Figure 9. Tensile stress-deflection curves for non-aerated and aerated slurry-infiltrated chicken mesh. ....16
Figure 10. Typical appearance of a failed tension test specimen of aerated slurry-infiltrated chicken mesh at
relatively large tensile deformations. ...........................................................................................................16
Figure 11. Flexure stress-deflection curves for non-aerated and aerated slurry-infiltrated chicken mesh
sheets. ...........................................................................................................................................................18
Figure 12. Flexural failure modes of non-aerated and aerated slurry-infiltrated chicken mesh sheets. ......18
Figure 13. Cross-section and flexural strain distribution of an aerated slurry infiltrated chicken mesh
rectangular section. ......................................................................................................................................21
Figure 14. The chicken mesh used in the experimental program. ................................................................24
Figure 15. The screws and nails used in the test program ............................................................................25
Figure 16. The pullout test setup. .................................................................................................................26
Figure 17. The test setup used for evaluation of the lateral behavior of a screw or nail in an aerated slurryinfiltrated chicken mesh sheet. .....................................................................................................................26
Figure 18. Nail configurations and test setups used in experimental evaluation of the lateral behavior of
nails under cyclic loads .................................................................................................................................27
Figure 19. Time-displacement curve for cyclic tests .....................................................................................28
Figure 20. A typical common nail pullout load-deflection behavior. ............................................................29
ix

Figure 21. Typical appearance of the aerated slurry-infiltrated chicken mesh sheet after pullout of a screw
......................................................................................................................................................................30
Figure 22. Typical lateral load-deflection behavior of exterior screw in aerated slurry-infiltrated chicken
mesh sheets of different bulk densities. .......................................................................................................31
Figure 23. Lateral load-deflection behavior of exterior screw in aerated slurry-infiltrated chicken mesh
sheets with different numbers of chicken mesh layers. ...............................................................................31
Figure 24. Visual appearance of aerated slurry-infiltrated chicken mesh sheets after failure under lateral
loading of a screw. ........................................................................................................................................32
Figure 25. Typical load-displacement curves in cyclic lateral loading of nails with different configurations
applied to aerated slurry-infiltrated chicken mesh sheets............................................................................33
Figure 26. Typical appearances of sheets and nails after performance of cyclic lateral tests: (a) sheet with
nails aligned parallel to the loading direction; (b) sheet with nails aligned perpendicular to the loading
direction; and (c) nails. .................................................................................................................................33
Figure 27. Typical load-displacement curve obtains from cyclic connection test, (a) exterior screw with 101.6
mm length and 4.19 mm diameter, (b) common nail with 101.6 mm length and 4.19 mm diameter .........34
Figure 28. Preparation of foamed water. ......................................................................................................36
Figure 29. The chicken mesh used in this experimental program. ...............................................................37
Figure 30. Chicken mesh orientations: longitudinal (left), and transverse (right). .......................................37
Figure 31. Cross-section and flexural strain distribution of aerated slurry infiltrated chicken mesh. ..........40
Figure 32. Construction of the aerated slurry-infiltrated chicken mesh frame.............................................41
Figure 33. The test setup used for performance of cyclic tests on the aerated slurry-infiltrated chicken mesh
frame.............................................................................................................................................................43
Figure 34. Plastic hinge formation in beam near the beam-column joint under reversed cycling testing with
growing displacement amplitudes. ...............................................................................................................44
Figure 35. The hysteretic response, and the initial and stabilized envelopes of the frame subjected to cyclic
loading per SPD (ASTM E2126) test method. ...............................................................................................45
Figure 36. Averaged initial and stabilized envelope curves of the aerated slurry-infiltrated chicken mesh
frame.............................................................................................................................................................45
Figure 37. Averaged initial envelope curves of the aerated slurry-infiltrated chicken mesh frame versus
those of lateral load-carrying systems based on OSB and hardwood...........................................................46
Figure 38. Definition of the EEEP curve (ASTM E2126). ................................................................................46
x

Figure 39. The initial and stabilized envelope curves of the aerated slurry-infiltrated chicken mesh frame,
and the EEEP curve corresponding to the initial envelope. ..........................................................................47
Figure 40. Elastic stiffness of different sheathing materials .........................................................................48
Figure 41. An example of chicken mesh........................................................................................................54
Figure 42. Infiltration of the chicken mesh layers placed in a form with aerated slurry. ..............................54
Figure 43. Typical tensile stress-strain behavior of aerated slurry-infiltrated chicken mesh. .......................55
Figure 44. The setup used for flexure testing of aerated slurry-infiltrated chicken mesh sheets. ................55
Figure 45. Punching shear test setup ............................................................................................................56
Figure 46. (a)Flexure test setup, (b) Shear test setup. ..................................................................................57
Figure 47. A schematic depiction of the side view of the aerated slurry-infiltrated chicken mesh column test
specimen. ......................................................................................................................................................58
Figure 48. The subcomponent comprising one frame with two sheets nailed to it. ....................................59
Figure 49. Test setup for cyclic in-plane lateral loading of the subcomponent with one frame. ..................59
Figure 50. Test setup for cyclic lateral loading of the subcomponent comprising two frames with sheets
nailed to their interior and exterior, and loading applied perpendicular to the frame planes. ....................59
Figure 51. Flexural load-deflection behavior of aerated slurry-infiltrated chicken mesh sheets ..................62
Figure 52. Aerated slurry-infiltrated chicken mesh sheet after flexural failure. ...........................................62
Figure 53. Punching shear load-deflection curves ........................................................................................63
Figure 54. Typical failure mode of aerated slurry-infiltrated chicken mesh sheets subjected to punching shear.
......................................................................................................................................................................63
Figure 55. Flexural behavior of aerated slurry-infiltrated chicken mesh beams: (a) typical failure mode; (b)
& (c) flexural load-deflection behavior of two beams. .................................................................................64
Figure 56. Flexural behavior under reversed loading: (a) test setup; (b) load-deflection behavior. .............65
Figure 57. Shear behavior of an aerated slurry-infiltrated chicken mesh beam: (a) failure mode; and (b) loaddeflection behavior. ......................................................................................................................................66
Figure 58. A typical compressive stress-deflection behavior of aerated slurry-infiltrated chicken mesh.....67
Figure 59. Hysteretic in-plane behavior of aerated slurry-infiltrated chicken mesh frame with and without
nailed sheets. ................................................................................................................................................68

xi

Figure 60. Failure modes of the subcomponent comprising a frame with two sheets nailed to it. .............69
Figure 61. Hysteretic behavior of the aerated slurry-infiltrated chicken mesh building subcomponent
comprising two frames with interior and exterior wall and ceiling/roof sheets nailed to it, and subjected to
cyclic lateral loading perpendicular to the plane of frames..........................................................................70
Figure 62. Failure modes of the subcomponent comprising two frames with sheets nailed to their interior
and exterior, and loading applied perpendicular to the frame planes. ........................................................70
Figure 63. Seismic forces applied at two levels: roof and mid-height. .........................................................75
Figure 64. Building frames. ...........................................................................................................................77
Figure 65. Deformation of a building frame subjected to horizontal seismic forces in the short direction of
the building. ..................................................................................................................................................78
Figure 66. Cross-section and flexural strain distribution of aerated slurry-infiltrated chicken mesh. ..........81
Figure 67. Aerated slurry infiltrated chicken mesh beam and column cross sections in building frames. ...83
Figure 68. Schematics of the aerated slurry-infiltrated chicken mesh footing. ............................................88
Figure 69. Top view of the footing. ...............................................................................................................88
Figure 70. Forces transferred to nails under lateral loads applied in the plane of wall sheets. ...................92
Figure 71. Accelerated rain-heat exposure testing of a sheet specimen: (a) water spray; (b) radiant heating.
......................................................................................................................................................................96
Figure 72. Visual appearance of aerated slurry-infiltrated chicken mesh sheets subjected to different
accelerated aging conditions. .......................................................................................................................97
Figure 73. Flexural strength test results. .......................................................................................................99
Figure 74. Effects of the number of wet-dry cycles on the flexural load-deflection behavior of aerated slurryinfiltrated chicken mesh sheets. .................................................................................................................100
Figure 75. Effects of the number of freeze-thaw cycles on the flexural load-deflection behavior of aerated
slurry-infiltrated chicken mesh sheets. .......................................................................................................100

xii

CHAPTER 1
INTRODUCTION
1.1.

General

The goal of this research was to develop building structural materials and systems that can make
effective use of locally available materials and construction resources. The building structure that
evolved through this research program is now under construction for verification of its constructability
and seismic performance via shaking table tests.
Aerated concrete with bulk densities less than 1 g/cm3 is generally viewed as a non-structural material
that offers thermal insulation qualities. It was found in this research investigation that a reinforcement
system with high specific surface area, close spacing and desired mechanical bonding with matrix
would enable use of aerated concrete in structural applications. Chicken mesh (poultry netting) was
used in this investigation as a commonly available reinforcement that meets the requirements for
transforming aerated concrete into a structural material. Viable volume (and area) fractions of chicken
mesh for structural applications produce a high degree of congestion with the formwork. Therefore,
an aerated slurry of high flowability was used to thoroughly infiltrate the congested reinforcement
system, facilitating thorough consolidation and desired interfacial interactions. The mesh behaves as
a homogeneous reinforcement to produce lightweight cementitious composites with a desired
balance of strength-to-weight ratio, ductility and toughness (Wafa and Fukuzawa 2010). Ferrocement,
a cementitious mortar with wire mesh reinforcement, provided the inspiration for development of
aerated slurry-infiltrated chicken mesh (Naaman 2000).
1.2.

Summary of Research

This thesis is divided into six chapters, with Chapters 1 through 5 prepared as a stand-alone paper
written for submission to a scientific journal. A sixth chapter is devoted to structural design of the
1

building system. For convenience, the references from each chapter have been consolidated and
appear at the end of this thesis. A brief review of each chapter is presented below.
1.2.1. Mechanical Properties of Aerated Slurry-Infiltrated Chicken Mesh
Aerated slurry-infiltrated chicken mesh was evaluated as a ductile and lightweight material for
building construction. The compressive strength of the aerated slurry, and the tensile, co pressive
and flexural behavior of the aerated slurry-infiltrated chicken mesh were evaluated. The system
exhibited a ductile failure mode which can be attributed to the high specific surface area and the
desired mechanical interlocking of the chicken mesh reinforcement. The presence of chicken mesh
was found to significantly alter the compressive strength of the aerated slurry. The effects of aeration
on the system behavior were evaluated. A theoretical basis was developed for evaluating the
mechanical behavior of aerated slurry-infiltrated chicken mesh.
1.2.2. Screw and Nail Behavior in Aerated Slurry-Infiltrated Chicken Mesh
Aerated slurry-infiltrated chicken mesh is developed as a lightweight building material which offers
some key features of wood construction in terms of ease of construction, combined with the desired
moisture resistance and durability characteristics of concrete. The aerated slurry-infiltrated chicken
mesh building components can be joined using nails or preferably screws. An experimental
investigation was conducted on the pullout as well as the unilateral and cycled lateral behavior of
nails and screws applied to aerated slurry-infiltrated chicken mesh. These attributes of nails and
screws strongly impact the structural behavior of building systems subjected to gravity and lateral
(including seismic) forces. It was found that the interactions between nails or screws and the chicken
mesh reinforcement in aerated slurry provides the screws or nails with desired lateral load-bearing
capacity, ductility, and hysteretic energy absorption capacity. The nails and screws applied to aerated

2

slurry-infiltrated chicken mesh also exhibited desired pullout behavior.
1.2.3. Behavior of a Lightweight Frame Made with Aerated Slurry-Infiltrated Chicken Mesh Under
Cyclic Lateral Loading
Aerated slurry-infiltrated chicken mesh is a ductile and light-weight material for seismic-resistant
building construction. An aerated slurry-infiltrated chicken mesh frame was subjected to cyclic lateral
loading in order to assess its load-bearing capacity, ductility and hysteretic energy dissipation capacity.
The frame exhibited a ductile failure mode compatible with its strong column-weak beam design. It
also exhibited a desirable hysteretic energy dissipation capacity. Comparisons were made between the
performance characteristics of this frame versus those of structural systems of similar geometric
attributes made primarily of wood-based sheets. Semi-empirical models were developed for
prediction of the structural behavior of aerated slurry-infiltrated chicken mesh. The structural
performance of the frame made with aerated slurry-infiltrated chicken mesh under cyclic lateral loads
was compared against those of lateral load-resisting systems of comparable geometric attributes
comprising primarily of OSB and hardwood sheets.
1.2.4. Structural Evaluation of a Lightweight Building System Made with Locally Available Materials
Aerated slurry-infiltrated chicken mesh was evaluated as a lightweight structural material for building
construction. The building system comprises frames and sheets, all of which contribute towards
resisting gravity and lateral loads. Structural joining of the building components involves application
of screws. Experimental investigations were undertaken to evaluate the performance of aerated
slurry-infiltrated chicken mesh frame elements (beams and columns) and sheets under different
force systems (bending moment, shear, punching shear, compression). A scaled structural
subcomponent comprising aerated slurry-infiltrated chicken mesh frames to which sheets were

3

screwed was also tested under cyclic lateral loads. Structural analysis methods were developed for
aerated slurry-infiltrated chicken mesh.
1.2.5. Structural Design of a Lightweight Building System Made with Locally Available Materials
The design loads of aerated slurry-infiltrated chicken mesh buildings were decided. The critical
factored load combinations were identified. The aerated slurry-infiltrated chicken mesh frames, wall
and roof/ceiling sheets and floor panels, and screws joining the sheets to building frames were
designed to safely resist the governing load combinations.
1.2.6. Durability Characteristics of Aerated Slurry-Infiltraetd Chicken Mesh
The effects of accelerated weathering on the flexural performance of aerated slurry-infiltrated
chicken mesh sheets were evaluated. This lightweight building material has been developed for
convenient construction of affordable, safe and energy-efficient buildings using locally available
materials and resources. External sheets that envelope the building are subjected to weathering
exposure. Investigations were performed on the effects of accelerated weathering on the flexural
performance of aerated slurry-infiltrated chicken mesh sheets. Standard methods of accelerated
aging developed for cementitious siding and roofing sheets were followed. Two test methods
involving exposure of sheets to wetting-drying and freezing-thawing cycles were implemented.
Aerated slurry-infiltrated chicken mesh sheets were found to perform desirably under these
accelerated aging effects.

4

CHAPTER 2
MECHANICAL PROPERTIES OF AERATED SLURRY-INFILTRATED CHICKEN MESH
2.1.

Introduction

Aerated concrete is traditionally viewed as an insulating (non-structural) building material. A primary
premise of the work reported herein is that a reinforcement system with high specific surface area and
desired mechanical bonding within matrix would enable use of aerated concrete in structural
applications. There is a growing interest in the use of wire mesh reinforcement in concrete panels.
Within certain limits, the mesh behaves as homogeneous reinforcement, and produces concrete
composites with highly desired tensile strength-to-weight ratio, cracking behavior and impact
resistance(Wafa and Fukuzawa 2010). Ferrocement, a cementitious mortar with wire mesh
reinforcement, benefits from these advantages associated with the use of nearly isotropic
reinforcement systems of high specific surface area and desired mechanical bonding (Naaman 2000).
Chicken mesh (poultry netting) was used as a readily available reinforcement system of high specific
surface area with desired mechanical bonding potential in aerated slurry. Viable volume (and area)
fractions of chicken mesh for structural applications produce a high degree of congestion with the
formwork. Therefore, an aerated slurry of high flowability was used to thoroughly infiltrate the
congested reinforcement system, facilitating thorough consolidation and desired interfacial
interactions.
Streamlined methods were devised for producing aerated slurry-infiltrated chicken mesh as a
structural material. An experimental program was conducted in order to gain insight into the
mechanical performance of this material. The effects of chicken mesh reinforcement on the
compressive strength of aerated slurry was investigated. The effect of aeration of slurry on the system
performance was also evaluated. A semi-empirical theoretical basis was developed for the mechanical
5

behavior of aerated slurry-infiltrated chicken mesh.
2.2.

Experimental Program

2.2.1. Materials
2.2.1.1. Aerated Slurry
The slurry mix was prepared in this investigation with Type I Portland cement and tap water. In one of
the mixtures, in order to achieve a viable fresh mix workability, a polycarboxylate-based
superplasticizer was used. The aerated slurry was prepared by adding a foaming agent to the mixing
water of slurry. Aeration introduces a homogenous system of fine air bubbles into the cement paste.
This is accomplished using foaming agents that stabilize the air voids generated by agitating the mixing
water of slurry to which the foaming agent has been added (Nambiar and Ramamurthy 2007,
Ramamurthy, Nambiar et al. 2009, Zhang, Provis et al. 2014). Preparation of the aerated slurry started
with production of foamed water. For this purpose, a foaming agent extracted from plants (saponin)
was blended with the mixing water at 1200 rpm rotational speed using a mixing blade attached to a
drill (Figure 1). The resulting foamed water was then added to cement, and mixed in a mortar mixer
for 6 minutes.

(a) Prior to stirring

(b) Foaming after stirring

Figure 1. Preparation of foamed water by stirring the mixing water incorporating the foaming agent.

6

2.2.1.2. Chicken Mesh
This work chose chicken mesh (hexagonal 20-gauge galvanized poultry netting) as a steel
reinforcement system of high specific surface area. This selection was made due to the broad
worldwide availability of chicken mesh. The common mesh used in this investigation was made of steel
wires of 1 mm diameter (0.785 mm2 cross sectional area). Chicken meshes are available with different
wire diameters and spacings. The spacing of hexagonally configured wires generally increase with
increasing wire diameter in order to provide comparable wire cross-sectional areas per unit width.
Given the relatively large layers of chicken mesh that need to be infiltrated with aerated slurry, the
preference in this investigation was for chicken meshes with larger wire diameter and spacing. The
chicken mesh used in this investigation was non-isotropic. The stronger direction (vertical in Figure 2)
is referred to as longitudinal in this work.

Figure 2. The chicken mesh used in the experimental program.
2.2.2. Experimental Methods
An experimental program was conducted in order to evaluate the effects of some key variables on the
mechanical properties of aerated slurry-infiltrated chicken mesh under compressive, flexural and
tensile loading. The interactions of chicken mesh with aerated slurry can be characterized as more
complex than those between concrete and conventional reinforcing bars. More attention should be

7

paid to the contributions of the aerated (slurry) matrix towards timely mobilization of the load-bearing
capacity of the multiple chicken mesh layers tightly incorporated into the aerated slurry. Test results
would be critical to understanding these complex interactions. Aerated slurry-infiltrated chicken mesh
can, due to the high specific surface area of steel reinforcement, provide distinctly high levels of
ductility and energy dissipation capacity. In addition, the high specific surface area and close spacing
of chicken mesh wires could benefit various aspects of the aerated slurry performance, including its
compressive strength, dimensional stability and resistance to shrinkage cracking. The experimental
methods used for evaluating the mechanical behavior of aerated slurry-infiltrated chicken mesh are
presented in the following. The experimental were used to develop semi-empirical models for
predicting the mechanical performance of aerated slurry-infiltrated chicken mesh.
2.2.2.1. Tests performed on slurry without chicken mesh reinforcement
The experimental work reported here used one non-aerated slurry as control, and different aerated
slurry mixtures. The non-aerated slurry comprised cement: water: superplasticizer at 1: 0.36: 0.004
weight ratios. For the purpose of preparing the aerated slurry mixtures, the foaming agent was added
to water and subjected to stirring at relatively high speed in order to product foamed mixing water,
which was then added to cement and mixed using normal mixing procedures. The water/cement ratio
of aerated slurry mixtures ranged from 0.40 to 0.55. The aerated slurry mix proportions are introduced
in Table 1 The resulting aerated slurry was placed in 50 mm cube molds for compression strength test
and bulk density measurement. The specimens kept in sealed condition at room temperature for 24
hour and cured at 95% relative humidity and room temperature for 7 days.

8

Table 1. The aerated slurry mix proportions.
Mix Foaming Agent Dosage, % by wt.
0

0

1

0.005%

2

0.01%

3

0.02%

4

0.005%

5

0.01%

6

0.02%

7

0.005%

8

0.01%

9

0.015%

10

0.02%

11

0.025%

12

0.03%

13

0.02%

14

0.025%

Water/cement ratio
0.35 with 0.004 superplasticizer
0.45

0.50

0.55

0.6

2.2.2.2. Tests performed on aerated slurry-infiltrated chicken mesh
The prismatic compression test specimens had planar dimensions of 102 mm by 102 mm, with a height
of 229 mm. The chicken mesh configuration used in compression testing of aerated slurry-infiltrated
chicken mesh specimens is presented in Figure 3. There were two groups of chicken mesh in these
specimens: (i) 30 interior layers placed in folded form; and (ii) four exterior layers wrapped around the
interior layers to mitigate the potential for split cracking upon screw application to the surface. Along
the height, where the chicken mesh layers are oriented in their strong direction, the total number of
chicken mesh layers is thus 38. The aerated slurry mixture comprised cement: water: saponin at 1: 0.6:
0.00045 weight ratios.

9

Figure 3. Aerated slurry-infiltrated chicken mesh compression test specimen.
Aerated slurry0infiltrated chicken mesh sheets with 20 mm thickness and 150 mm width were
subjected to tension testing. The number of chicken mesh layers in different tension test specimens
varied from 12 to 24. The chicken mesh layers were oriented to that the tensile force was resisted in
their strong direction. The tension test setup is shown in Figure 4. The free length of the tension test
specimen between the two grips was 310 mm (with a total specimen length of 500 mm). Tension tests
were performed at a constant displacement rate of 0.05 mm/s. The values of load and deflection were
recorded during the tension tests using a data acquisition system.

Figure 4. Tension test setup.
The aerated slurry-infiltrated chicken mesh sheets tested in flexural had the same dimensions as the
10

tension test specimens. They were subjected to four-point flexure loading over a span of 450 mm. Load
was applied quasi-statically (with a constant displacement rate of 0.033 mm/s), and load-deflection
data were collected during the flexure test up to failure.

Figure 5. Flexure test setup.
2.3.

Test Results and Discussion

2.3.1. Compressive strength and bulk density of aerated slurry
The aerated slurry mix designs, defined by the foaming agent dosage (expressed as wt.% of cement)
and water/cement ratio, were presented in Table 1. The measured values of 7-day compressive
strength and bulk density are presented in Table 2 and Figure 7. Lower values of bulk density tend to
correspond with lower compressive strength values. This is both because of the rise in air content and
also the increase in water/cement ratio at higher dosages of foaming agent for achieving viable fresh
mix rheology. Mix #13 with density of 0.9 g/cm3 and compressive strength of 5.4 MPa at 7 days
provides a viable balance of bulk density and strength for the targeted application. When compared
with non-aerated slurry, it can be noted that aeration of slurry (Mix #13) produced 61% drop in bulk
density and 90% drop in compressive strength. This work emphasized reduction of density in order to
limit seismic forces (Guo, Juan et al. 2011, Ohsaki, Miyamura et al. 2016) and also allow for manual
installation of the building structural components. It was hypothesized that the presence of closely
11

spaced chicken mesh wires with high specific surface area would benefit the compressive strength of
aerated slurry-infiltrated chicken mesh.
Table 2. Compressive strength and bulk density of different aerated slurry mixtures (Mix 0 is nonaerated).
Mix 7-Day Compressive Strength, MPa Bulk Density, g/cm3
0

50

2.2

1

10.7

1.9

2

8.2

1.5

3

6.3

1.4

4

14.1

1.2

5

10.5

1.81

6

9.2

1.3

7

13.3

1.6

8

11.1

1.7

9

9.4

1.3

10

6.4

1.17

11

2.4

0.65

12

1.2

0.8

13

5.4

0.9

14

7.1

1.12

12

(a). Compressive strength and bulk density test results for different aerated slurries.

(b). Compressive strength and bulk density test results for different aerated slurries.
Figure 6. Compressive strength and bulk density test results for different aerated slurries.
2.3.2

Compressive behavior of the aerated slurry-infiltrated chicken mesh

A typical compressive stress-deflection curve for an aerated slurry-infiltrated chicken mesh prepared
with the aerated slurry Mix #13 is presented in Figure 7. The presence of chicken mesh significantly
improved the compressive strength and ductility of the aerated slurry. The aerated slurry alone
provided a compressive strength of 5.4 MPa. In the presence of chicken mesh, a strain-hardening
behavior was observed after this strength levels was reached. The ultimate strength was more than
13

15 MPa, noting that the specimen was unloaded after the maximum deflection limit of the test
system was reached at about 70 mm. One can attribute the observed strain-hardening behavior (and
the corresponding rise in compressive strength) of the aerated slurry-infiltrated chicken mesh partly
to the confining effect rendered by the wire mesh with closely spaced wires of high specific surface
area.
16
14

Stress, MPa

12
10
8
6
4
2
0
0

10

20

30

40

Deflection, mm

50

60

70

80

Figure 7. A typical compressive stress-deflection behavior of aerated slurry-infiltrated chicken mesh.
2.3.3

Tensile behavior of aerated slurry-infiltrated chicken mesh

The three slurries considered in this experimental program provided bulk densities (after hardening
and air-drying) of: (1) 2.2 g/cm3; (2) 1.3 g/cm3; and (3) 0.8 g/cm3. The highest density of 2.2 g/cm3 was
obtained without aeration of slurry. The tensile load-deflection curves obtained with 18 layers of
chicken infiltrated with aerated (or non-aerated) slurry (producing a sheet of 25 mm thickness) are
presented in Figure 8 together with the load-deflection curve for 18 layers of chicken mesh obtained
without slurry-infiltration. The corresponding tensile stress-deflection curves for slurry-infiltrated
chicken mesh specimens are presented in Figure 10. Slurry infiltration is observed in Figure 8 to
significantly raise the stress levels (within the 0-30 mm deflection range considered here) of chicken
mesh layers. The misaligned configuration of chicken mesh wires make it significantly compromises its

14

stiffness and thus its merits as a tensile load-bearing system. The tendency towards realignment of
chicken mesh wires at small deflections seriously undermine its structural stiffness. Infiltration with
slurry (including aerated slurry), on the other hand, resists this tendency woards realignment of wires,
and thus enables mobilization of the tensile load-carrying capacity of the chicken mesh wires at
relatively small displacements. Aeration of the slurry to reduce its bulk density does not significantly
undermine its ability to mobilize the chicken mesh wires at small displacements to resist tensile forces.
In short, chicken mesh and aerated slurry exhibit synergistic effects in the context of aerated slurryinfiltrated chicken mesh. The confining effects of chicken mesh increases the compressive strength of
aerated slurry by more than 200%. Infiltration of chicken mesh with slurry also enables effects use of
the tensile load-carrying capacity of the chicken mesh wires at structurally viable deformation levels.
Reduction of the slurry density via aeration from 2.2 to 0.8 g/cm3 (by 63%) lowered the tensile strength
of aerated slurry infiltrated chicken mesh from 5.4 to 4.2 MPa (by only 22%), as shown in Figure 9. This
finding points at the potential of the aerated slurry-infiltrated chicken mesh to provide a desired
balance of low bulk density and relatively high tensile strength. The tensile stiffness of slurry-infiltrated
chicken mesh was not reduced significantly upon aeration for lowering its bulk density.
Figure 10 shows a tensile specimen of aerated slurry-infiltrated chicken mesh after failure in tension.
A distributed damage zone was observed where the tendency towards realignment of chicken mesh
wires, that was resisted by the aerated slurry surrounding the wires, led to crushing of the aerated
slurry at large deformations.

15

Non-aerated slurry infiltrated chicken mesh

25

1.3 g/cm3 density aerated slurry infiltrated
chicken mesh
0.8 g/cm3 density aerated slurry infiltrated
chicken mesh

Tensile Load, kN

20

15

10

5

0
0

5

10

15

Deflection, mm

20

25

30

Figure 8. Tensile load-deflection curves for non-aerated and aerated slurry-infiltrated chicken mesh,
and also for chicken mesh tested alone (without slurry-infiltration).
Non aerated slurry infiltrated
chicken mesh
1.3 g/cm3 density aerated slurry
infiltrated chicken mesh
0.8 g/cm3 density aerated slurry
infiltrated chicken mesh

6

Stress, MPa

5
4
3
2
1
0
0

5

10

15

Deflection, mm

20

25

30

Figure 9. Tensile stress-deflection curves for non-aerated and aerated slurry-infiltrated chicken mesh.

Figure 10. Typical appearance of a failed tension test specimen of aerated slurry-infiltrated chicken
mesh at relatively large tensile deformations.
16

The tensile strengths obtained for the slurry-infiltrated chicken mesh sheets presented above are
summarized in Table 3. While the slurry density and the number of chicken mesh layers influence the
tensile strength of aerated slurry-infiltrated chicken mesh sheets (with high concentration of chicken
mesh), all these tensile strengths (except when 6 or 9 layers of chicken mesh are used) occur within a
relatively narrow 3.64 – 4.40 MPa range. Significant reduction of bulk density could be obtained via
aeration of the slurry without significant loss of the slurry-infiltrated chicken mesh tensile strength.
These observations point at the potential of aerated slurry-infiltrated chicken mesh to provide a
desired balance of tensile strength and bulk density.
Table 3. A summary presentation of the tensile strength test results for slurry-infiltrated chicken
mesh sheets with different slurry densities and number of chicken mesh layers.

Slurry

Chicken
Mesh
Layers

Saponin/Cement
(weight ratio)

Water/Cement
(weight ratio)

Bulk
Density
(g/cm3)

Tensile Strength
(MPa)

0.36*

NonAerated

18/24

-

(0.004
superplasticizer)

2.2

5.48/ 5.60

Aerated

16/18

0.0002

0.5

1.3

3.71/ 4.40

0.0005

0.6

0.8

1.67/2.65/3.64/4.20

Aerated

6/9/12/
18

Superplasticizer at 0.004 by weight of cement
2.3.4

Flexural performance

The three slurries considered in this experimental program provided bulk densities (after hardening
and air-drying) of: (1) 2.2 g/cm3; (2) 1.3 g/cm3; and (3) 0.8 g/cm3. The highest density of 2.2 g/cm3 was
obtained without aeration of slurry. Typical flexural stress-deflection curves for sheets of 25 mm
thickness made with non-aerated and aerated slurries using 18 layers of chicken mesh are presented
in Figure 11. The flexural behavior is observed to be ductile. Aeration of slurry lowered the flexural

17

strength but not the ductility of the aerated slurry-infiltrated chicken mesh. Increasing the dosage of
foaming agent to reduce the bulk density of the aerated slurry from 1.3 to 0.8 g/cm3 had relatively
small effects on the flexural performance of the resultant sheets. The peak flexural stress obtained
with aerated slurry of 0.8 g/cm3 bulk density was 6.9 MPa. Reduction of the aerated slurry density
from 1.3 to 0.8 (by 38%) led to a reduction of the flexural stress from 7.8 MPa to 6.9 MPa (by 11%).
The flexure test specimens prepared with non-aerated slurry exhibited multiple cracking and a
distributed flexural failure mode (Figure 12a); flexural failure of the aerated specimens was less
distributed (Figure 12).
25
Nonaerated slurry
infiltrated chicken
mesh

Stress, MPa

20
15

1.3 density aerated
slurry infiltrated
chicken mesh

10

0.8 density aerated
slurry infiltrated
chicken mesh

5
0
0

10

20

30

40

50

Deflection, mm

Figure 11. Flexure stress-deflection curves for non-aerated and aerated slurry-infiltrated chicken
mesh sheets.

(a) Non-aerated slurry

(b) Aerated slurry

Figure 12. Flexural failure modes of non-aerated and aerated slurry-infiltrated chicken mesh sheets.
18

2.3.5

Analysis of aerated slurry-infiltrated chicken mesh

The aerated slurry makes significant indirect contributions toward tensile strength by restraining the
chicken mesh wires (which are partly oriented at an angle with respect to the tensile stress siewxrion)
from reorientation under tensile stress. The tensile strength of aerated slurry-infiltrated chicken mesh
was expressed as follows:
𝜎𝑇 = 𝛼𝜌𝑓𝑦
where, σT = tensile strength of the aerated slurry infiltrated chicken mesh, ρ = area ratio of the chicken
mesh wires, fy = yield stress of the chicken mesh wires (310 MPa), and Îą = an empirical efficiency factor
which reflects the degree of restraint offered by the aerated slurry against reorientation of the chicken
mesh layers as well as the orientations of wires with respect to the tensile stress direction. An average
value of 𝛼 = 0.26 allows for prediction of the experimental values of tensile strength using the above
equation.
In compression, one should account for the direct contribution of the chicken mesh wires (embedded
in the aerated slurry matrix), and also their indirect confining effect which raises the effective
compressive strength of the slurry. Considering these contributions of chicken mesh, the composite
compressive strength of aerated slurry-infiltrated chicken mesh may be expressed as follows:
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′
where, σc = compressive strength of the aerated slurry-infiltrated chicken mesh, β = efficiency factor
for the chicken mesh reinforcement in compression (it was assumed to be similar to the empirically
derived efficiency factor of chicken mesh in tension, that is 0.26), and Îł = efficiency factor of the
aerated sully in compression, which benefits from the confining effect of the chicken mesh
reinforcement. A Îł value of 4.6 allowed the above equation to predict the compression test results

19

performed on aerated slurry-infiltrated chicken mesh. In other words, the aerated slurry that benefits
from the beneficial effects of chicken mesh provides 4.6 times the compressive strength of plain
aerated slurry. These relatively large beneficial effects can be attributed to: (i) the relatively low elastic
modulus and high Poisson’s ratio of the aerated slurry that produce relatively large strains in
compression which, are restrained by the chicken mesh reinforcement of high elastic modulus and
specific surface area with closely spaced wires, resulting in confining effects which raise the aerated
slurry compressive strength; (ii) chicken mesh with high specific surface area and close wire spacing
effectively reinforces the aerated slurry against the microcrack formation under restrained shrinkage,
and the growth of these microcracks under load. The rise in compressive strength of aerated slurry
with chicken mesh reinforcement is a significant factor enabling the otherwise non-structural
(insulating) aerated slurry to make contributions to the aerated slurry-infiltrated chicken mesh
structural performance.
Using concepts similar to those used with reinforced concrete, the nominal flexural strength (Mn) of
an aerated slurry-infiltrated chicken mesh cross-section (Figure 13) can be expressed as follows:
ℎ
𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)( )
2
where, ‘a’ is a value related to (and somewhat smaller than) the depth of neutral axis (c), and b and h
are, respectively, the width and height of a rectangular cross-section. Similar to the approach to
reinforced concrete flexural analysis, a constant compressive stress is assumed up to depth ‘a’ in order
to simulate the nonlinear compressive stress distribution up to the depth neutral axis depth of ‘c’. The
value of ‘a’ can be derived based on the equilibrium of the tensile and compressive forces generated
at the section under bending moment:
𝛼𝜌𝑓𝑦 (ℎ − 𝑎) = (𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ )𝑎

20

Figure 13. Cross-section and flexural strain distribution of an aerated slurry infiltrated chicken mesh
rectangular section.
As a first step, the expression derived above for the nominal flexural strength of aerated slurryinfiltrated chicken mesh was verified using the experimental data generated for a beam and two
sheets made with aerated slurry-infiltrated chicken mesh. These structural test specimens were
made with a slurry proportioned at saponin: water: cement weight ratios of 0.00045: 0.6: 1 (which
yielded a bulk specific gravity of 0.8 after hardening and air-drying). Table 4 presents the aerated
slurry-infiltrated chicken mesh sheet dimensions, reinforcement conditions, test results, and the
experimental and theoretical values of flexural strength. The theoretical values of flexural strength
obtained with the expression presented above are observed to be less than experimental values by
only 3 to 5%. The approach outlined above for calculation of the nominal flexural strength of aerated
slurry-infiltrated chicken mesh sheets and beams thus yielded favorable accuracy based on the
limited test data generated in this investigation.

21

Table 4. Aerated slurry-infiltrated chicken mesh sheet and beam dimensions, reinforcement and
loading conditions, and test results versus predicted values.

Specime
n

# of
Chicke
n
Mesh
Layers

Span
,
mm

Widt
h,
mm

Thicknes
s, mm

Rein
f.
Area
Rati
o

Densit
y,
g/cm3

Sheet

12

450

150

20

0.04

0.8

Sheet

18

450

150

25

0.03

0.8

Beam

30

800

102

254

0.02

0.8

22

Peak
Load,
N

3 or 4
Point
Loadin
g

1300

Flexural
Strength, N.m
Test

Theory

4

97.5

92.67

2500

4

180.
5

170.41

2500
0

3

5000

4910.24
8

CHAPTER 3
SCREW AND NAIL BEHAVIOR IN AERATED SLURRY-INFILTRATED CHICKEN MESH
3.1.

Introduction

Aerated concrete is traditionally viewed as an insulating (non-structural) building material. The work
reported herein employs a readily available reinforcement system (chicken mesh) of high specific
surface area and desired mechanical bonding with matrix to enable structural applications of aerated
concrete. Within certain limits, the mesh behaves as homogeneous reinforcement, and produces
lightweight cementitious composites with highly desired tensile strength-to-weight ratios, cracking
behavior, ductility, toughness and impact resistance (Wafa and Fukuzawa 2010). Ferrocement, a
cementitious mortar with wire mesh reinforcement, benefits from these advantages associated with
the use of nearly isotropic reinforcement systems of high specific surface area and desired mechanical
bonding (Naaman 2000). Aerated slurry-infiltrated chicken mesh differs from ferrocement by the
aeration of the matrix for weight reduction, and use of a flowable slurry for infiltration of the slurry
between the closely spaced wires of chicken mesh, noting that the relatively fine diameter of the
chicken mesh wires (when compared with the mesh reinforcement commonly used in ferrocement)
yields closer wire spacings.
Joining of the aerated slurry-infiltrated chicken mesh with screws or nails is an important factor in
simplifying the construction process. Nail and screw behavior would strongly impact the structural
performance (including seismic resistance) of aerated slurry-infiltrated chicken mesh building
systems (ASTM 2012). The ductility and hysteretic energy absorption capacity of screws or nails in
shear play an important role in dissipating the seismic energy input to the building (Rosowsky and
Reinhold 1999, Ganne-Chedeville, Pizzi et al. 2005). The approach to seismic design of aerated slurryinfiltrated chicken mesh building systems emphasizes adequate strength and ductility of nails or
23

screws in pullout and lateral behavior, and their ability to provide favorable hysteretic behavior for
dissipating the input energy of earthquakes (Dolan and Madsen 1992, Herzog and Yeh 2006).
3.2.
3.2.1

Material and Methods
Materials

Saponin was used as the foaming agent for production of aerated slurry. The saponin used in this
investigation was obtained from plants. The work reported herein was performed using Type I
Portland cement; other hydraulic cements could also be used in this application. The slurry used here
had a water/cement ratio of 0.6; the saponin/cement ratios considered here were 0.0005 and
0.00035, which produced hardened material bulk densities of 0.78 g/cm3 and 0.9 g/cm3, respectively.
The chicken mesh used in this investigation was hexagonal 20-gauge galvanized poultry netting
(Figure 14). This commonly available mesh is made of steel wires of 1 mm diameter (with 0.785 mm 2
cross sectional area).

Figure 14. The chicken mesh used in the experimental program.
Three types of screw and two types of nail were considered in this test program (Figure 15). The
screws were: (i) Philips bugle-head coarse thread sharp point polymer coated exterior screw (#10 x 4
in.) with 101.6 mm length and 4.19 mm diameter (Model # PTN4S1, for exterior use); (ii) Philips
bugle-head coarse thread sharp point polymer coated exterior screw (#10 x 3-1/2 in.) with76.2 mm
length and 3.5 mm diameter (Model # PTN312S1, for exterior use); and (iii) Philips zinc-plated flat24

head wood screws (#14 x 4 in.) with 101.6 mm length and 6.02mm (Model # 807791, for both
interior and exterior use). The two nails were: (i) Common nail Model 20HGC1, for interior use (#6 x
4 in.) with 101.6 mm length with 4.19 mm diameter; and (ii) Pro-fit 010202ddeck nail (20D x 4 in),
hot dip galvanized with 101.6 mm length and 4.19 mm diameter. These screws and nails were
applied perpendicular to the plane of aerated slurry-infiltrated chicken mesh sheets.

(a) Screws

(b) Nails

Figure 15. The screws and nails used in the test program
3.2.2

Test Methods

The screw and nail pullout test setup is shown in Figures 16. A servovalve-controlled hydraulic test
system was used to pull a screw or nail out at a rate of 1.5 mm/min (ASTM 2012). A data acquisition
system collected the load and deflection test data from a load cell and a displacement transducer
throughout the pullout process. The aerated slurry-infiltrated chicken mesh sheets used in pullout
tests were 80 mm thick with 300 mm by 300 mm planar dimensions. They were reinforced with 30
layers of chicken mesh. The slurry was simply poured onto the chicken mesh; it was fluid enough to
thoroughly infiltrate the chicken mesh layers within the sheet thickness. Tests were performed after
7 days of moist curing (at room temperature) of the aerated slurry-infiltrated chicken mesh sheets.

25

Figure 16. The pullout test setup.
The test setup used for evaluating the monotonic lateral behavior of screws and nails acting against an
aerated slurry-infiltrated chicken mesh sheet is shown in Figure 17. The sheet used for this purpose
was 15 mm thick with 500 mm x 500 mm planar dimensions. It was reinforced with 12 layers of chicken
mesh. Test were performed after moist curing of the sheets for 7 days at room temperature. The
monotonic lateral tests were performed at a crosshead speed of 6 mm/min. The load-deflection
behavior was monitored via collection of data using a a data acquisition system from load cell and a
displacement transducer.

Figure 17. The test setup used for evaluation of the lateral behavior of a screw or nail in an aerated
slurry-infiltrated chicken mesh sheet.
26

The cyclic lateral tests were performed two screws or nails applied in two configurations, as shown in
Figure 18. In the first configuration (Figure 18a), the center of the first screw or nail was at 5 cm
distance from the sheet edge, and the center-to-center spacing of the screws or nails was 5 cm. In the
second configuration (Figure 18b), both screws or nails were centered at 5 cm from the sheet edge,
and their center-to-center spacing was 7.5 cm.

1.

Screws or nails aligned parallel to the loading direction

(b) Screws or nails aligned perpendicular to the loading direction
Figure 18. Nail configurations and test setups used in experimental evaluation of the lateral behavior
of nails under cyclic loads
Cyclic tests were performed quasi-statically at a frequency of 0.09 Hz; the sine function used in this
27

cyclic testing is shown in Figure 19 and summarized in Table 5. The four cycles marked ‘stabilizing cycles’
were used to achieve a stabilized hysteretic curve. A degradation of no more than 5% shall be present
between successive cycles. If a larger degradation exists, tests shall be repeated with a higher number
of cycles within this set (Dolan and Madsen 1992, Dolan 1994) in order to determine the level at which
the performance stabilizes. This stabilized hysteresis curve is used to calculate the stabilized energy
dissipation of the connection (Kazantzi and Vamvatsikos 2012), and provides conservative estimates
of the performance parameters that would be expected in structures previously loaded or subjected
to a large number of cycles during a loading event (Uang and Bertero 1990).

Deflection, mm

30
20
10
0

-10 0

20

40

60

80

100

120

140

-20
-30

Time, s

Figure 19. Time-displacement curve for cyclic tests
Table 5. The displacement cycles used in lateral testing of nails.

Number of Cycles Maximum Displacement, mm Displacement Rate (sine function)
Âą6.4
4

Âą12.7

0.09 Hz

Âą19.0
3.3.
3.3.1

Test Results and Discussion
Screw or Nail Pullout Behavior in Aerated Slurry-Infiltrated Chicken Mesh

Figure 20 presents a typical pullout load-deflection behavior of the common nail introduced earlier

28

from an aerated slurry-infiltrated chicken mesh sheet with 18 layers of chicken mesh (with 0.78 bulk
specific gravity of aerated slurry). A peak pullout load of 183 N was obtained in this specific test. The
nail pullout behavior is observed to be ductile.
Pullout Load, kN

0.2
0.15
0.1
0.05
0
0

10

20

30

40

Deflection, mm

Figure 20. A typical common nail pullout load-deflection behavior.
The screw and nail pullout test data generated for different screw or nail sizes and sheet
thicknesses/number of chicken mesh layers are summarized in Table 6. It was necessary to pre-drill a
hole of smaller diameter prior to application of screw to aerated slurry-infiltrated chicken mesh the
diameter of the (masonry) drill bits used for this purpose are presented in Table 6. In general, screws
exhibited a better pullout performance than nails. The galvanized spiral nail produced a better
pullout behavior than the common nail. The pullout behavior of nails and screws from aerated slurryinfiltrated chicken mesh benefited significantly from increasing the bulk density of the aerated slurry.
Figure 21 shows a typical appearance of the aerated slurry-infiltrated chicken mesh sheet after
pullout of a screw.

29

Table 6. Summary of the screw and nail pullout test results.
Bulk Density of the Aerated
Slurry-Infiltrated Chicken Mesh,
g/cm3

Drill Bit
Diameter,

Common nail of 101.6 mm length
and 4.19 mm diameter

0.78

-

183

Common nail of 101.6 mm length
and 4.19 mm diameter

0.90

-

365.5

Galvanized spiral nail of 101.6
mm length and 4.19 mm
diameter

0.78

-

567.6

Exterior screw of 76.2 mm length
and 3.5 mm diameter

0.78

3.17

1050

Exterior screw of 101.6 mm
length and 4.19 mm diameter

0.78

3.17

1270

Zinc-coated wood screw of 101.6
mm length and 6.02 mm
diameter

0.78

4.76

3080

Nail or Screw Type

mm

Peak Pullout
Force, N

Figure 21. Typical appearance of the aerated slurry-infiltrated chicken mesh sheet after pullout of a
screw
3.3.2

Screw or Nail Lateral Behavior in Aerated Slurry-Infiltrated Chicken Mesh Sheets

Typical lateral load-deflection behavior of an exterior screw of 101.6 mm length and 4.19 mm
diameter in aerated slurry-infiltrated chicken mesh with 0.78 g/cm3 and 0.9 g/cm3 bulk densities are
presented in Figure 22. Unlike the pullout behavior, the lateral behavior of screws does not change
notably with changing the aerated slurry bulk density. Figure 23 presents typical screw lateral
behavior in aerated slurry-infiltrated chicken mesh sheets with 4, 8 and 12 layers of chicken mesh.

30

The increase in the number of chicken mesh layers is observed to significantly benefit the lateral
load-carrying capacity and the ductility of the screw lateral behavior. Closer observation of failure
modes under lateral loading (Figure 24) indicated that the lateral behavior of screws (and also nails)
in aerated slurry-infiltrated chicken mesh is largely a result of the interactions of screws with the
chicken mesh reinforcement. This observation explains the significant effects of the number of
chicken mesh layers on the screw lateral behavior. At extreme levels of bulk density, the screw or nail
lateral behavior could be affected by the bulk density of the aerated slurry. This is because the tensile
behavior of chicken mesh within aerated slurry-infiltrated chicken mesh depends upon the
restraining effect of the aerated slurry matrix which is a function of the modulus and strength of the

Lateral Load, kN

aerated slurry.
0.9 bulk density aerated slurryinfiltrated chicken mesh
0.78 bulk density aerated
slurry-infiltrated chicken mesh

3.5
3
2.5
2
1.5
1
0.5
0
0

10

20

30

Deflection, mm

40

50

60

Figure 22. Typical lateral load-deflection behavior of exterior screw in aerated slurry-infiltrated
chicken mesh sheets of different bulk densities.
3
4 layers
8 layers
12 layers

Load, kN

2.5
2
1.5
1
0.5
0
0

10

20

30

Deflection, mm

40

50

60

Figure 23. Lateral load-deflection behavior of exterior screw in aerated slurry-infiltrated chicken
mesh sheets with different numbers of chicken mesh layers.
31

Figure 24. Visual appearance of aerated slurry-infiltrated chicken mesh sheets after failure under
lateral loading of a screw.
3.3.3

Screws and Nail Cyclic Lateral Behavior in Aerated Slurry-Infiltrated Chicken Mesh Sheets

Figure 25 presents typical cyclic load-displacement curves obtained with two-common nail of 101.6
mm length and 4.19 mm diameter applied to aerated slurry-infiltrated chicken mesh sheets. The sheets
and the nails after application of cyclic tests are shown in Figure 26. The nails essentially cut into the
aerated slurry, but had to drag the layers of chicken mesh in the process (with nails themselves
experiencing some plastic deformations in the process). This behavior led to a pinched but stable
hysteretic behavior. At each displacement level, the load could be largely restored under repeated
displacement cycles. In the case with nails aligned parallel to the load direction (Figure 25a), that is
not very relevant to the indigenous building system considered here, the hysteretic energy dissipation
at each displacement level occurred in the first cycle, with minimal energy dissipation occurring in
subsequent cycles of the same displacement. Increased displacement levels, however, restored the
energy dissipation capacity of nails during the first cycle. The peak load continued to increase with
increasing deformation (within the range considered here), which is due to the resistance provided by
the chicken mesh layers that are dragged with the nail. With nails perpendicular to the load direction
(Figure 25b), the peak load as well as the hysteretic energy dissipation are more favorable. Peak loads
32

approach twice those obtained with nails aligned parallel to the load direction. As far as the hysteretic
energy dissipation capacity is concerned, subsequent cycles at constant displacement provide reduced
(compared to the first cycle) but still notable energy dissipation capacity (that is unlike the case with
nails aligned parallel to the load direction). The peak load continues to increase with increasing

Load, kN

displacement, but at a faster pace than that observed with nails aligned parallel to the load direction.

-25

-15

2
1.5
1
0.5
0
-5
-0.5
-1
-1.5
-2

5

15

25

Deflection, mm

(a) Nails aligned parallel to load

(b) Nails aligned perpendicular to load

Figure 25. Typical load-displacement curves in cyclic lateral loading of nails with different
configurations applied to aerated slurry-infiltrated chicken mesh sheets.

(a)

(b)

(c)

Figure 26. Typical appearances of sheets and nails after performance of cyclic lateral tests: (a) sheet
with nails aligned parallel to the loading direction; (b) sheet with nails aligned perpendicular to the
loading direction; and (c) nails.

33

Figure 27a presents typical cyclic lateral load-displacement curves obtained with the single exterior
screw of 101.6 mm length and 4.19 mm diameter applied to an aerated slurry-infiltrated chicken mesh
sheet. Figure 27b presents typical cyclic load-deflection curves for a single common nail of 101.6 mm
length and 4.19 mm diameter tested similar to the screw. The peak load continues to increase with
increasing displacement within the displacement range considered here. The values of load at similar

Load, kN

deflections were comparable for the nail and the screw which had similar lengths and diameters.

3
2
1
0

-21

-16

-11

-6

-1

-1

4

9

14

19

Deflection, mm

-2
-3

(a) Specimen with screw

(b) Specimen with common nail

Figure 27. Typical load-displacement curve obtains from cyclic connection test, (a) exterior screw
with 101.6 mm length and 4.19 mm diameter, (b) common nail with 101.6 mm length and 4.19 mm
diameter

34

CHAPTER 4
BEHAVIOR OF A LIGHTWEIGHT FRAME MADE WITH AERATED SLURRY-INFILTRATED CHICKEN MESH
UNDER CYCLIC LATERAL LOADING
4.1.

Introduction

Aerated concrete is traditionally viewed as an insulating (non-structural) building material. A primary
premise of the work reported herein is that a reinforcement system with high specific surface area
would enable use of aerated concrete in structural applications. The high specific surface area and the
confining role of such reinforcement was hypothesized to benefit the structural performance of
aerated concrete. Construction with reinforcement systems of high specific surface area would be
challenged by the congestion of reinforcement which is not favorable to convenient placement and
consolidation of aerated concrete. An aerated slurry of high flowability was used in this work to
thoroughly penetrate the congested reinforcement system, facilitating thorough consolidation and
desired interfacial interactions with the reinforcement. This work chose chicken mesh (hexagonal 20gauge galvanized poultry netting) as a steel reinforcement system of high specific surface area due to
its broad availability across the world.
Concrete structures generally rely on frames as the primary lateral load-resisting structural systems
(Arroyo and GutiĂŠrrez 2016, Abd-Elhamed and Mahmoud 2017, Ruiz-GarcĂ­a and Aguilar 2017).
Reinforced concrete frames can be designed to provide high levels of ductility and (hysteretic) energy
dissipation capacity for efficient resistance of seismic forces. Aerated slurry-infiltrated chicken mesh
can, due to the high specific surface area of steel reinforcement, provide distinctly high levels of
ductility and energy dissipation capacity. The work reported herein evaluated the structural
performance of an aerated slurry-infiltrated chicken mesh from under cyclic lateral loads (He, Lam et
al. 1998, Rose 1998). The data generated on the ductility, hysteretic energy absorption capacity and

35

the lateral load-bearing capacity of the frame, accompanied with structural analyses of the frame,
provide insight into the merits of aerated slurry-infiltrated chicken mesh as a robust building material
for construction of seismic-resistant building systems.
4.2.

Materials and Methods

4.2.1. Aerated Slurry
Aeration introduces a homogenous system of fine air bubbles into the cement paste. This is
accomplished using foaming agents that stabilize the air voids generated via agitation of the mixing
water of slurry that incorporates the foaming agent (Nambiar and Ramamurthy 2007, Ramamurthy,
Nambiar et al. 2009, Zhang, Provis et al. 2014). Preparation of the aerated slurry started with
production of foamed water. For this purpose, a foaming agent extracted from plants (saponin)
blended with the mixing water at 1200 rpm rotational speed, using a mixing blade attached to a drill
(Figure 28). The foamed mixing water was then added to cement at water/cement ratio of 0.5. Mixing
was accomplished in a mortar mixer for 2 minutes.

Figure 28. Preparation of foamed water.
The aerated slurry used to infiltrate the chicken mesh (Figure 3b) comprised cement: water: saponin
at 1: 0.5: 0.0006 weight ratios, with a bulk density in hardened state of 0.9 g/cm3. Cube specimens of
plain aerated slurry with 50 mm dimensions were also prepared for performance of compression tests.
The molded specimens were stored in sealed condition (>95% relative humidity) at room temperature)
for 7 days, and then subjected to compression testing. The average compressive strength was
36

measured at 5 MPa.
4.2.2. Chicken Mesh
The chicken mesh considered in this experimental program (Figure 29) comprised wire gauge No. 20
(with 0.88 mm diameter, 0.608 mm2 cross sectional areas) configured hexagonally with wire spacing
of 25 mm. Chicken meshes are available with different wire diameter and spacing. Commonly available
chicken meshes are made with wires of different diameters; the spacing of hexagonally configured
wires are generally increased with increasing wire diameter in order to provide comparable wire crosssectional areas per unit width. Given the relatively large layers of chicken mesh that need to be
infiltrated with aerated slurry, the preference in this investigation was for chicken meshes with larger
wire diameter and spacing. Figure 30 depicts the anisotropic structure of chicken mesh, which provides
higher strength in the longitudinal direction and lower strength in the transverse direction.

Figure 29. The chicken mesh used in this experimental program.

Figure 30. Chicken mesh orientations: longitudinal (left), and transverse (right).
4.2.3. Aerated Slurry-Infiltrated Chicken Mesh
Given the fine diameter of the chicken mesh wires, a relatively low volume fraction (e.g., 1%) of chicken
mesh produces a relatively congested reinforcement system. As a result, cementitious materials with
37

normal fresh mix rheology cannot be used in this application. The need to infiltrate multiple layers of
chicken mesh led to the selection of a flowable slurry as the binder for use with chicken mesh
reinforcement. Aerated slurry was used in this application to lower the density of structural materials
for ease of installation and reduction of seismic forces. Aerated concrete is usually used as insulation
and not in structural applications. It was hypothesized that the high specific surface area and the
confining action of chicken mesh would enhance the mechanical performance of the resultant aerated
slurry infiltrated chicken mesh to suit structural applications.
In chicken mesh, wires are oriented in different directions. Chicken mesh thus offers a high level of
flexibility when subjected to tension, which is due to a tendency towards alignment of wires along the
direction of tensile force. Their low stiffness excludes chicken mesh from structural applications. When
placed within a matrix (aerated slurry in this case), however, the wires in chicken mesh are restrained
against realignment by the matrix. Depending on the extent of this restraint, the tensile force-resisting
capacity of wires would be mobilized from the beginning. This raises the stiffness of chicken mesh,
which could translate aerated slurry infiltrated chicken mesh into a structural building material. Semiempirical equations were developed to express the tensile and compressive strengths of aerated slurry
infiltrated chicken mesh, as described below.
4.2.4. Aerated Slurry Infiltrated Chicken Mesh Frame
The models presented earlier predicting the flexural strength of aerated slurry infiltrated chicken
mesh were verified using the experimental results.
The tensile strength of aerated slurry infiltrated chicken mesh (σT) was expressed as follows:
𝜎𝑇 = 𝛼𝜌𝑓𝑦
where, ρ = area fraction of the chicken mesh wires (irrespective of their orientation) at a cross-section

38

that is perpendicular to the tensile stress direction; fy = yield stress of the chicken mesh wires (310
MPa); and Îą = an empirical efficiency factor which reflects the degree of restraint provided by the
aerated slurry against realignment of wires (0.56 based on experimental results).
In compression, the composite behavior of aerated slurry infiltrated chicken mesh produces a
compressive strength that can be expressed as follows:
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′
where, σc = compressive strength; β = efficiency factor of chicken mesh reinforcement in compressive
(it was assumed to be similar to the efficiency factor of chicken mesh in tension, that is 0.56); and Îł =
efficiency factor of aerated sully in compression, which was surprisingly found (in compression tests
performed on an aerated slurry infiltrated chicken mesh) to be quite large (close to 5).
Using concepts similar to those used with reinforced concrete, the nominal flexural strength (Mn) of
an aerated slurry-infiltrated chicken mesh cross-section (Figure 31) can be expressed as follows:
ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 )
where, ‘a’ was assumed to be equal to the depth of neutral axis c, considering the highly ductile
behavior of aerated slurry infiltrated chicken mesh. A constant compressive stress was assumed up to
depth ‘a’ in order to simulate the nonlinear compressive stress distribution. The value of ‘a’ can be
derived based on the equilibrium of tensile and compressive forces generated at the section subjected
to bending moment:
𝛼𝜌𝑓𝑦 (ℎ − 𝑎) = (𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ )𝑎

39

Figure 31. Cross-section and flexural strain distribution of aerated slurry infiltrated chicken mesh.
An aerated slurry infiltrated chicken mesh frame with 1.75 m height and 1.4 m width was designed to
withstand a concentrated in-plane load of 8 KN applied at its top. The maximum bending moment
under this loading condition is: M= Ft.h /2 = 7,000 N.m. The cross-section designed to resist this
bending moment had 10 cm width and 25 cm height, reinforced with 30 layers of chicken mesh (with
the chicken mesh layers oriented longitudinally along the element axis). The area fraction of
longitudinally oriented chicken mesh layers at cross-sections is 1.5%. The resultant tensile and
compressive strengths of the aerated slurry-infiltrated chicken mesh would be:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.56𝑥0.016𝑥310 = 2.75 𝑀𝑃𝑎
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.56x0.016x310 + 5x2.5 = 15.2776 MPa
Equilibrium of tensile and compressive forces can be used to calculate the value of ‘a’ (assumed to be
equal to the depth of neutral axis “c” in Figure 4) required for calculating the nominal flexural strength:
𝜎𝐶 . 𝑎 = 𝜎𝑇 . (ℎ − 𝑎)
15.2776xa = 2.75x (250-a)
a = 38.29 mm
The flexural strength of the aerated slurry infiltrated chicken mesh can now be calculated as:
ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 ) = 0.56x0.016x310x100x(250-38.29)x(250/2) = 7376.50 N.m
The nominal bending moment flexural strength of 7,376.5 N.m exceeds the required flexural strength

40

of 7,000 N.m by 5%.
Figure 32a shows the formwork with chicken mesh reinforcement placed in it. The slurry was simply
poured onto the chicken mesh (Figure 32b) to infiltrate the preplaced chicken mesh layers. After
pouring of slurry, the frame was covered with plastic sheet to mitigate moisture loss. This allowed for
curing at >95% relative humidity, that was achieved using the vapor released from the slurry during
curing. The frame was cured at ambient temperature for 14 days.

(a) Formwork with preplaced chicken mesh

(b) Infiltration of Chicken mesh

Figure 32. Construction of the aerated slurry-infiltrated chicken mesh frame.
4.2.5. Cyclic Testing
The frame behavior was evaluated under quasi-static cyclic lateral loading. The test procedure involved
application of reversed load cycles of progressively increasing lateral displacements until the first
major event (FME), defined here as yielding, occurred.

Three reversed cycles of progressively

increasing displacement amplitude were applied before the FME was reached. Subsequent loading
followed the Sequential Phase Displacement (SPD) procedure which involves application of
degradation and stabilization cycles at a constant displacement amplitude before progressing to the
next phase with a greater displacement. The first cycle in a phase is applied with a larger displacement,
and is proceeded by three degradation cycles; subsequent application of three stabilization cycles
completes the phase. Stabilized response is achieved when the decrease in resistance between two

41

successive stabilization cycles is less than 5% (Soudki, West et al. 1996). If the decrease in resistance
is more than 5%, additional stabilization cycles should be conducted. The frame tested in this study
stabilized in five cycles. The procedure then moves on to the next phase (Salenikovich, Dolan et al.
1999, Gatto and Uang 2003, Ibarra, Medina et al. 2005).
Cyclic testing of the frame was performed in accordance with ASTM E2126 Method A, that closely
follows the SPD procedure developed by TCCMAR (Porter 1987) with few modifications. The SPD
procedure is based solely on the First Major Event (FME), where FME is defined as the displacement
at which the structure starts to deform inelastically (anticipated yield displacement) (Krawinkler 2009).
ASTM E2126, on the other hand, takes into account both FME and ductility ratio when determining
the initial amplitude of each phase in the test protocol. In general, the SPD protocol is displacementcontrolled, and involves triangular reversed cycles at increasing displacement levels. The displacement
increase in ASTM E2126 is based on FME and ductility ratio. The SPD procedure begins with at least
three incremental levels of three cycles each, within the elastic displacement region up to the First
Major Event (FME). The SPD method recommends 200% of the FME as the displacement increment
for each phase in the case of ductile systems (Salenikovich, Dolan et al. 1999, Gatto and Uang 2003).
The test protocol devised here, based on ASTM E2126 requirement, comprised 15 steps of
displacement increase, with trailing cycles after each peak cycle as shown in Table 7.

42

Table 7. Test protocol for evaluation of the frame performance under cyclic lateral loads
Load
step

Drift

Peak Displacement,
cm

Trailing Cycle Displ.

# of trailing
cycles

1

0.050%

0.048

0.048

5

2

0.075%

0.072

0.054

6

3

0.100%

0.096

0.072

6

4

0.20%

0.192

0.144

3

5

0.3%

0.288

0.216

3

6

0.4%

0.384

0.288

3

7

0.7%

0.672

0.504

2

8

1.00%

0.960

0.720

2

9

1.50%

1.440

1.080

2

10

2.00%

1.920

1.440

2

11

2.50%

2.400

1.800

2

12

3.00%

2.880

2.160

2

13

4.00%

3.840

2.880

2

14

4.50%

4.320

3.240

2

15

5.00%

4.800

3.600

2

The column bases were fixed in an aerated slurry-infiltrated chicken mesh footing, and installed on a
reaction frame (Figure 33) for in-plane lateral cyclic loading per ASTM E564. A load cell and a
displacement transducer were used to collect the load and displacement data, using a data
acquisition system, under cyclic lateral loads.

Figure 33. The test setup used for performance of cyclic tests on the aerated slurry-infiltrated chicken
mesh frame.
43

4.3.

Test Results and Discussion

The frame failed by plastic hinge formation in beam, as expected from the strong column-weak beam
approach adopted for seismic design of the frame. Figure 34 shows the plastic hinge formation in
beam near the beam-column joint under repeated load cycles. The top part of the plastic hinge
exhibited multiple cracking, while one crack formed at the bottom, which widened and connected to
top cracks under cyclic deformations of growing amplitudes.

Figure 34. Plastic hinge formation in beam near the beam-column joint under reversed cycling testing
with growing displacement amplitudes.
The cyclic load-deflection curve produced for the frame is presented in Figure 35 together with the
initial envelope (connecting the initial peak loads at the initial load achieved for each displacement) as
well as the stabilized envelope (connecting the stabilized peak loads after repeated cycles at each
deformation) (Dolan and Heine 1997). The displacement cycles were unsymmetrical in this test due to
the size constraints of the reaction frame used in this test. Figures 36a and 36b shows the average
initial and stabilized envelopes, respectively, obtained by averaging the corresponding envelope curves
produced in opposite displacement directions (Dolan and Johnson 1996, Dolan and Heine 1997).

44

Figure 35. The hysteretic response, and the initial and stabilized envelopes of the frame subjected to

8
7
6
5
4
3
2
1
0

Load (kN)

Load (kN)

cyclic loading per SPD (ASTM E2126) test method.

0

20

40

60

Deflection (mm)

7
6
5
4
3
2
1
0
0

20

40

60

Deflection (mm)

(a) Initial envelope

(b) Stabilized envelope

Figure 36. Averaged initial and stabilized envelope curves of the aerated slurry-infiltrated chicken
mesh frame.
A comparative study was made of the behavior of the aerated slurry-infiltrated chicken mesh frame
versus lateral load-carrying system of similar geometric attributes comprising either oriented
strandboard (OSB) or hardwood subjected to comparable cyclic lateral loads (Toothman 2003). Figure
37 shows the average initial envelopes of these systems. The aerated slurry-infiltrated chicken mesh
frame is observed to provide ductility levels comparable to those of lateral load-carrying systems based
on OSB and hardwood. The peak load-carrying capacity of the frame is more than those of systems
based on OSB and hardwood; such comparisons, however, should also account for the weight of
different systems.
45

Figure 37. Averaged initial envelope curves of the aerated slurry-infiltrated chicken mesh frame
versus those of lateral load-carrying systems based on OSB and hardwood.
The envelope curves introduced above can be used, following the ASTM E2126 procedures, to derive
the Equivalent Energy Elastic Plastic (EEEP) curve that represents an elasto-plastic interpretation of the
aerated slurry-infiltrated chicken mesh behavior. The EEEP curve (Figure 11) encompasses the same
order of magnitude area as the actual load-displacement curve (form the origin to the ultimate
displacement). This area is a measure of the toughness of the system. Toughness is defined here as
the energy required to fail the structural system. The EEP curve shown in Figure 38 incorporates a yield
force(Pyield) and the corresponding displacement (Δyield), the failure displacement (Δu), the area under
the load-displacement curve, and the elastic stiffness of the structural system.

Figure 38. Definition of the EEEP curve (ASTM E2126).

46

Figure 39 shows the averaged initial and stabilized envelope curves of the slurry-infiltrated chicken
mesh frame, and also the EEEP curve corresponding to the initial envelope curve. Elastic stiffness, ke,
can be determined as the slope of the secant passing through the origin and the point on the loaddisplacement curve (or envelope curve) that is equal to 40% of the peak load, Fpeak. The slope of this
line is used to locate the elastic portion of the EEEP curve. In addition, it is used to find other
parameters such as the yield load, yield displacement, and the ductility ratio.(Kesner, Billington et al.
2003)
0.4𝐹𝑃𝑒𝑎𝑘

Elastic Stiffness = ke =∆

0.4𝐹𝑝𝑒𝑎𝑘

Elastic stiffness is a good indicator of the stiffness that a frame would exhibit when subjected to low
to moderate displacements (Salenikovich 2000). The elastic stiffness obtained using the initial
envelope curve for the aerated slurry-infiltrated chicken mesh following the above procedure is shown
in Figure 40, and compared with later load resisting systems of comparable geometry made with OSB
or hardwood sheeting. The elastic stiffness of the aerated slurry-infiltrated chicken mesh is observed
to be higher than those provided by alternative lateral load resisting systems

Figure 39. The initial and stabilized envelope curves of the aerated slurry-infiltrated chicken mesh
frame, and the EEEP curve corresponding to the initial envelope.
47

Figure 40. Elastic stiffness of different sheathing materials
Following the ASTM E2126 procedures, failure load was calculated as 80% of the peak load.
Displacement at failure is another key parameter in assessing the seismic resistance of a lateral loadcarrying system. The ability of a structure to dissipate energy arises partly from its ability to deform
without failing (Park 1989, Salonikios, Kappos et al. 2000). Table 8 compares the failure load and the
displacement at failure of the aerated slurry-infiltrated chicken mesh frame versus alternative lateral
load-resisting systems with comparable geometry which are made with oriented strandboard (OSB)
and hardwood sheathing. The aerated slurry-infiltrated chicken mesh frame is observed to provide a
relatively high failure load but lower displacement at failure when compared with the alternative
systems. A review of the initial envelopes of these systems, however, indicates that the overall ductility
of the three systems is comparable, and the relatively low displacement at failure of the aerated slurryinfiltrated chicken mesh frame is a result of the approach taken by ASMT E2126 to define this
displacement.

48

Table 8. Failure load and displacement at failure of aerated slurry-infiltrated chicken mesh frame
versus alternative lateral load-carrying systems of comparable geometric attributes.
Lateral Load-Carrying System

Failure Load, kN Displacement at Failure, mm

Aerated slurry w/chicken mesh

5.54

32.26

OSB

3.11

83

Hardboard

3.29

76

4.3.1. Yield load and yield displacement
Yield load is determined based on an approximation of the first major event, which is the theoretical
load and displacement at which the structure starts to deform inelastically . For the area under the
load-displacement curve and the EEEP curve to be equal, the value of Fyield is found where the area of
the load-displacement curve equals the area of the EEEP curve . The area under the load-displacement
curve (A) can be computed by integrating the initial envelope curve between x=0 to x=32.6 mm (the
failure displacement as presented in Table 9). The value of Fyield can then be calculated as follows:

𝐹𝑦𝑖𝑒𝑙𝑑 =

2𝐴
𝑘𝑒

−∆𝑢 ±√∆2𝑢 −
−1
𝑘𝑒

Where Fyield= Yield Load (Kip, KN), A = the area (kip.in, KN.mm) under the load-displacement curve
from the origin to the failure displacement (Δfailure), and ke = elastic Stiffness (kip/in, kN/mm). Once
Fyield is determined, the yield displacement can be calculated using the following relationship:
Yield Displacement (Δyield) =

𝐹𝑦𝑖𝑒𝑙𝑑
𝑘𝑒

49

Table 9. The parameters required for calculation of the yield load (and the calculated value of yield
load).
Parameter

Numerical value

A, mm2

255.2

Ke, KN/mm

0.659

Δfailure, mm

8.26

Fyield, KN

5.445

4.3.2. Ductility
Ductility is an important characteristic of a structural system, which reflects its ability to yield and
deform inelastically without failure. The ability of structural member to bend but not fail is important
exposure to sudden and powerful cycles of an intense earthquake. Different measures have been used
to express the ductility of a structure. The most commonly accepted definition is that of ASTM E2126,
which defines the ductility factor, Îź, as the ratio of the failure displacement to the yield displacement.
The ductility ratio, derived from test results, is defined as the displacement at failure load divided by
the displacement at yield load (Salenikovich, Dolan et al. 1999, Thomsen IV and Wallace 2004)
Ductility Ratio = Îź =

∆𝑓𝑎𝑖𝑙𝑢𝑟𝑒
∆𝑦𝑖𝑒𝑙𝑑

This value represents the relative displacement that a structure can undergo from yielding until failure.
It reflects the ability of ductile structural systems to undergo further displacements beyond Δpeak.
When the structural component has reached its capacity, it transfers additional load onto other
components. The ductility factor introduced above is the ratio of two displacements. If a structure
undergoes large deformations before failure but has a large yield displacement, the structure is not
necessarily a ductile system. The reverse is also true, so ductility should always be considered together
50

with other performance indicators. Although ductility is an important characteristic, it should be noted
that it is not a material property and caution should be used when comparing different structural
systems. Given the variations that exists when calculating the elastic stiffness and yield load, a large
margin for error and inconsistent results may be encountered.
The ductility factor of structural systems comprising sheathing materials varies from 4 to 10 for both
OSB and hardboard (Toothman 2003) , compared to a ductility factor of 10.9 calculated for the aerated
slurry infiltrated chicken mesh frame using Equation (8). The higher elastic stiffness of the frame tends
to reduce its yield displacement, which raises the calculated value of ductility. These results point at
the ductile behavior of the aerated slurry-infiltrated chicken mesh frame, and its ability to yield and
undergo inelastic deformation to dissipate the input energy of severe earthquake ground motions.

51

CHAPTER 5
STRUCTURAL EVALUATION OF A LIGHTWEIGHT BUILDING SYSTEM MADE WITH LOCALLY AVAILABLE
MATERIALS
5.1.

Introduction

Aerated concrete with bulk densities less than 1 g/cm3 is generally viewed as a non-structural material
that offers thermal insulation qualities(Narayanan and Ramamurthy 2000, Abdullah, Hussin et al. 2006,
Memon, Sumadi et al. 2006). The work reported herein employed chicken mesh (poultry netting) to
enhance the structural qualities of aerated concrete for load-bearing applications. Chicken mesh,
when used at 2-4 vol.% in aerated concrete, produces a composite material with significantly enhanced
mechanical properties that result from the synergistic actions of chicken mesh and aerated concrete
in the context of the composite materials. The term aerated concrete is altered to aerated slurry in this
application because a highly flowable aerated concrete would be needed to infiltrate the closely
spaced wires of chicken mesh used at the required volume fraction. The composite material is thus
referred to as ‘aerated slurry-infiltrated chicken mesh’. In this composite, the high specific surface area
of chicken mesh and the close spacing of its wires significantly enhance the compressive strength and
the dimensional stability of the aerated slurry. The restraining effects of the aerated slurry against
reorientation of the chicken mesh wires, on the other hand, enables mobilization of the tensile loadcarrying capacity of the chicken mesh wires at structurally viable deformations. These synergistic
effects produce a lightweight composite material with a desired balance of compressive and tensile
strengths, ductility and toughness. The combination of aeration of matrix and use of chicken mesh at
2-4 vol.% enables application of screw (and nail) for joining of aerated slurry-infiltrated chicken mesh
components. The interactions of screws with the aerated slurry and the layers of chicken mesh
reinforcement provides for highly ductile behavior when screws are subjected to pullout and lateral

52

loads.
Ferrocement is the building system with attributes similar to aerated slurry-infiltrated chicken mesh.
(Aboul-Anen, El-Shafey et al. 2009, Ahmad, Arif et al. 2014)The matrix in ferrocement is commonly a
conventional (normal-weight) mortar of relatively low flowability, which is troweled into layers of mesh
that are generally coarser than chicken mesh(Naaman 2000, Sreevidya, Anuradha et al. 2012), with
smaller specific surface area and greater spacing of wires (rods). Minor work has been performed on
ferrocement with chicken mesh reinforcement (Naaman 2000, Wafa and Fukuzawa 2010).
An experimental investigation was conducted in order to comprehend the structural performance of
aerated slurry-infiltrated chicken mesh building elements and subcomponents(Desayi and Reddy 1991,
Krawinkler 2009, Heinzmann, Etter et al. 2012). Structural analysis techniques were developed for this
building system, and a building structure was designed with aerated slurry-infiltrated chicken mesh.
5.2 Experimental Program
5.2.1

Introduction

Structural elements and subcomponents made with aerated slurry-infiltrated chicken mesh were
evaluated under different force systems. The elements evaluated here included sheets, beams and
columns. The subcomponents tested in this experimental program included frames with sheets
screwed to it, which were subjected to cyclic lateral loading (representing seismic effects).
5.2.2

A Brief Review of the Material Properties of Aerated Slurry-infiltrated Chicken Mesh

Aerated slurry-infiltrated chicken mesh is produced by preparing a highly flowable aerated slurry of
0.6 water/cement ratio and bulk density of less than 1 g/cm3. This investigation was performed with
aerated slurries of 0.75 and 0.9 g/cm3 bulk density. Structural elements are produced by preplacing
the required chicken mesh layers in the formwork, followed by infiltration of the chicken mesh layers

53

with aerated slurry. Figure 41 shown a chicken mesh, and Figure 42 depicts the process of infiltrating
the chicken mesh layers placed in a form with aerated slurry. Chicken mesh is used in this application
at 2-4% volume fraction. The anisotropic nature of chicken mesh requires their orientation so that
the strongest direction is aligned with the direction of largest tensile stresses.

Figure 41. An example of chicken mesh.

Figure 42. Infiltration of the chicken mesh layers placed in a form with aerated slurry.
The tensile strengths provided by aerated slurry-infiltrated chicken mesh range from 1.6 to 5 MPa,
their flexural strengths from 3 to 8 MPa, and compressive strength from 15 to 20 MPa. Figure 43
shows a typical tensile stress-strain relationship of aerated slurry-infiltrated chicken mesh. The
ductile behavior observed here in tension is also noted under flexural and compressive load systems.

54

Stress, MPa

5
4
3
2
1
0
0

0.02

0.04

0.06

0.08

Strain

Figure 43. Typical tensile stress-strain behavior of aerated slurry-infiltrated chicken mesh.
5.2.3

Aerated Slurry-Infiltrated Chicken Mesh Sheets

The aerated slurry used for preparation of sheets comprised cement: water: saponin (foaming agent)
at 1: 0.6: 0.00045 weight ratios. Aerated slurry-infiltrated chicken mesh sheets were subjected to
flexure and punching shear tests. The chicken mesh used in this investigation was made with wires of
0.88 mm diameter and 310 MPa yield strength. Sheets of different thickness and number of chicken
mesh layers were tested in Flexure (Table 10). The chicken mesh layers were aligned so that their
stronger (longitudinal) direction was oriented with the direction of the tensile stress generated under
flexural loading. The sheets subjected to flexural loading had length and width of 1219 and 609 mm,
respectively. They were subjected to three-point loading over a span of 1,000 mm. The flexure test
setup is shown in Figure 44. Flexural loading was applied quasi-statically following the general
procedures of ASTM D790.

Figure 44. The setup used for flexure testing of aerated slurry-infiltrated chicken mesh sheets.
55

Table 10. The thickness, number of chicken mesh layers, and the volume fraction and cross-section
area fraction of chicken mesh reinforcement.
Specimen No. Thickness, mm

Chicken Mesh Reinforcement
No. of Layers Volume Fraction, % Area Fraction, %

1

25.40

12

3.63

3.04

2

31.75

16

3.87

3.24

3

38.10

18

3.63

3.04

4

50.80

24

3.63

3.04

The aerated slurry-infiltrated chicken mesh sheets subjected to punching shear tests were 609 mm by
609 mm planar dimensions with the following thickness and reinforcement conditions: (i) 25.4 mm
thickness and 12 layers of chicken mesh (3.6% chicken mesh volume fraction); and (ii) 31.75 mm
thickness and 16 layers of chicken mesh (3.8% chicken mesh volume fraction). The punching shear test
setup is shown in Figure 45. The specimen was loaded on a 5 cm diameter area, with the four corners
of the specimen fixed (Guandalini, Burdet et al. 2009, Heinzmann, Etter et al. 2012). The values of load
and deflection were recorded during the tests.

Figure 45. Punching shear test setup
5.2.4

Aerated Slurry-Infiltrated Chicken Mesh Beams

Three similar aerated slurry-infiltrated chicken mesh beams were tested under lateral loading, with
load configurations selected to encourage flexural failure in two beams, and shear failure in the third
one. The width and height of the beam cross sections were 102 mm and 229 mm, respectively. The

56

total beam lengths were 1,006 mm and 520 mm, respectively. The test spans of the beams were 900
and 500 mm in flexure and shear tests, respectively. The chicken mesh reinforcement in beams
comprised 30 layers of mesh places in folded form, and e layers of mesh wrapped around them. The
total number of chicken mesh layers was thus 38 layers distributed rather uniformly around the full
height. The strong direction of chicken mesh was oriented along the length of the beam specimens.
The flexure and shear test setups are shown in Figures 46, respectively. Flexure tests were performed
under three-point loading. In shear tests, two loads were applied at 100 mm distance from each
support. Loads were applied quasi-statically using a servovalve-controlled hydraulic cement system
up to failure (Aboul-Anen, El-Shafey et al. 2009). Loads and deflections were monitored throughout
tests using load cells, deflection transducers and a high-speed data acquisition system.

(a)

(b)

Figure 46. (a)Flexure test setup, (b) Shear test setup.
5.2.5

Aerated Slurry-Infiltrated Chicken Mesh Columns

Prismatic aerated slurry-infiltrated chicken mesh column specimens were tested in compression. The
column specimens were 102 mm by 102 mm in cross-section, with a total height of 229 mm. The
chicken mesh reinforcement in columns were similar to those in beams described earlier. A side view
of the column specimen is schematically depicted in Figure 47.

57

Figure 47. A schematic depiction of the side view of the aerated slurry-infiltrated chicken mesh
column test specimen.
5.2.6

Aerated Slurry-Infiltrated Chicken Mesh Subcomponents

The subcomponent test specimens comprised aerated slurry-infiltrated chicken mesh frames to which
aerated slurry-infiltrated chicken mesh sheets were nailed. Two categories of subcomponents were
tested. One (Figure 48) comprised one frame with two sheets nailed to both its sides. The other
category (Figure 50) comprised two frames with interior and exterior (wall, ceiling and roof) sheets
nailed to it. The subcomponent with one frame was subjected to cyclic lateral loading in the plane of
the frame (Figure 49). A frame (without sheets nailed to it) was also tested for comparison purposes.
The subcomponent with two frames was subjected to cyclic lateral loading out of the plane of the
frames (Figure 50). The lateral loads in both cases were applied at the beam level, with the columns
bases spaced in rigid footings that were fixed to the test frame.
The aerated slurry-infiltrated chicken mesh sheets used in these tests were 25.4 mm thick with 12
layers of chicken mesh reinforcement. The frames comprised beams and columns with 102 width and
254 mm height. The height and width of the frames were 1.75 and 1.4 m, respectively. The nails used

58

here had a diameter of 4.12 mm, and a length of 101.6 mm, the nails were applied at a spacing of 26
cm.

Figure 48. The subcomponent comprising one frame with two sheets nailed to it.

Figure 49. Test setup for cyclic in-plane lateral loading of the subcomponent with one frame.

Figure 50. Test setup for cyclic lateral loading of the subcomponent comprising two frames with
sheets nailed to their interior and exterior, and loading applied perpendicular to the frame planes.

59

A servovalve-controlled hydraulic actuator was used to apply quasi-static cyclic lateral loads to the
building subcomponents per ASTM E564. Loads and deflections were monitored throughout the tests
using a load cell and a displacement transducer with a high-speed data acquisition system. The test
procedure involved application of reversed load cycles of progressively increasing lateral
displacements until the occurrence of the first major event (FME), defined here as yielding. Three
reversed cycles of progressively increasing displacement amplitude were applied before the FME was
reached. Subsequent loading followed the Sequential Phase Displacement (SPD) procedure which
involves application of degradation and stabilization cycles at a constant displacement amplitude
before progressing to the next phase with a greater displacement. The first cycle in a phase is applied
with a larger displacement, and is proceeded by three degradation cycles; subsequent application of
three stabilization cycles completes the phase. Stabilized response is achieved when the decrease in
resistance between two successive stabilization cycles is less than 5% (Soudki, West et al. 1996). If the
decrease in resistance is more than 5%, additional stabilization cycles should be conducted. The frame
tested in this study stabilized in five cycles. The procedure then moves on to the next phase
(Salenikovich, Dolan et al. 1999, Gatto and Uang 2003, Ibarra, Medina et al. 2005).
Cyclic testing of the frame was performed in accordance with ASTM E2126 Method A, that closely
follows the SPD procedure developed by TCCMAR (Porter 1987) with few modifications. The SPD
procedure is based solely on the First Major Event (FME), where FME is defined as the displacement
at which the structure starts to deform inelastically (anticipated yield displacement) (Krawinkler 2009).
ASTM E2126, on the other hand, takes into account both FME and ductility ratio when determining
the initial amplitude of each phase in the test protocol. In general, the SPD protocol is displacementcontrolled, and involves triangular reversed cycles at increasing displacement levels. The displacement

60

increase in ASTM E2126 is based on FME and ductility ratio. The SPD procedure begins with at least
three incremental levels of three cycles each, within the elastic displacement region up to the First
Major Event (FME). The SPD method recommends 200% of the FME as the displacement increment
for each phase in the case of ductile systems (Salenikovich, Dolan et al. 1999, Gatto and Uang 2003).
The test protocol devised here, based on ASTM E2126 requirement, comprised 15 steps of
displacement increase, with trailing cycles after each peak cycle as shown in Table 11.
Table 11. Test protocol for evaluation of the frame performance under cyclic lateral loads

Load step

Drift

Peak Displacement, cm

Trailing Cycle Displ.

# of
trailing
cycles

1

0.050%

0.048

0.048

5

2

0.075%

0.072

0.054

6

3

0.100%

0.096

0.072

6

4

0.20%

0.192

0.144

3

5

0.3%

0.288

0.216

3

6

0.4%

0.384

0.288

3

7

0.7%

0.672

0.504

2

8

1.00%

0.960

0.720

2

9

1.50%

1.440

1.080

2

10

2.00%

1.920

1.440

2

11

2.50%

2.400

1.800

2

12

3.00%

2.880

2.160

2

13

4.00%

3.840

2.880

2

14

4.50%

4.320

3.240

2

15

5.00%

4.800

3.600

2

5.3 Experimental Results
5.3.1

Aerated Slurry-Infiltrated Chicken Mesh Sheets

Typical flexural load-deflection curves for the aeriated slurry-infiltrated chicken mesh sheets are
presented in Figure 51. The flexural behavior is observed to be ductile. Specimens with lower chicken

61

mesh ratios produce lower flexural strengths. The sheet with 12 layers of chicken mesh
reinforcement (and 25.4 mm thickness) provided the highest peak load of 2.2KN. Figure 12a shows a
typical sheet specimen after flexural failure. Typical crack patterns underneath the test specimens

Load, kN

are shown in Figure 52b. Failure exhibited a somewhat distributed nature.
10

24 layers

8

18 layers

6

16 layers
12 layers

4
2
0
0

20

40

60

80

100

120

140

Deflection, mm

Figure 51. Flexural load-deflection behavior of aerated slurry-infiltrated chicken mesh sheets

Figure 52. Aerated slurry-infiltrated chicken mesh sheet after flexural failure.
Figure 53 shows the load-deflection curves obtained in two punching shear tests performed on
aerated slurry-infiltrated chicken mesh sheets with different numbers of chicken mesh layers. The
sheets with 12 and 16 layers of chicken mesh were 25.4 and 31.75 mm thick, respectively. The peak
load in punching shear increased with increasing number of chicken mesh layers (which
accompanied increasing thickness), and the behavior was ductile. Both specimens performed
favorably in punching shear; the loaded area could not penetrate through the sheet specimen even
after 45 mm of displacement. The chicken mesh reinforcement effectively mitigated penetration of
62

the small loaded area into the sheet (Figure 54).

Load, kN

8
16 layers

6

12 layers

4
2
0
0

10

20

30

40

50

Deflection, mm

Figure 53. Punching shear load-deflection curves

(a) Failed specimen

(b) Failure mode underneath the loaded area

Figure 54. Typical failure mode of aerated slurry-infiltrated chicken mesh sheets subjected to
punching shear.
5.3.2

Aerated Slurry-Infiltrated Chicken Mesh Beams

A beam test specimen under flexural loading is shown in Figure 55a. Failure of aerated slurry-infiltrated
chicken mesh beams involved multiple cracking over an extended length of the beam. Figures 55b and
55c shows the load-deflection behavior of the two beams tested in this experimental program. Failure
was highly ductile, with the peak load retained over large deformations. The nature of tensile failure
in aerated slurry-infiltrated chicken mesh beam was different from those observed in reinforced
concrete. Besides the formation of closely spaced multiple cracks, a tendency towards crushing of the
aerated slurry was also noted, which could be attributed to the bearing action of the chicken mesh
wires against aerated slurry. Given this failure mode, one of the beams was subjected to reverse
63

loading (Figure 56a) after failure under original loading in order to gain an initial insight into its cyclic
behavior. As shown in Figure 56b, the peak load under reverse loading approached that under the
original loading direction.

(a)

(b)
30

Load, kN

25
20
15
10
5
0
0

20

40

Deflection, mm

60

(c)
Figure 55. Flexural behavior of aerated slurry-infiltrated chicken mesh beams: (a) typical failure
mode; (b) & (c) flexural load-deflection behavior of two beams.
64

Load, KN

(a)
30
20
10
0
-100

-80

-60

-40

-20

0
-10

20

40

60

80

100

Deflection, mm

-20
-30

(b)
Figure 56. Flexural behavior under reversed loading: (a) test setup; (b) load-deflection behavior.
Under shear loading, aerated slurry-infiltrated chicken mesh exhibited high strength levels (about five
times that obtained in flexure). The shear failure mode and load-deflection behavior are shown in
Figure 57. Besides a high shear strength, the beam also failed in a ductile manner in shear. The
distinctly favorable shear behavior of aerated slurry-infiltrated chicken mesh can be attributed to: (i)
the dual role of chicken mesh, which is distributed across the thickness as both flexural and shear
reinforcement; (ii) the highly ductile behavior of aerated slurry-infiltrated chicken mesh in shear; and
(iii) the high specific surface area of the chicken mesh wires which benefits their dowel action against

65

the aerated slurry.

(a)

(b)
Figure 57. Shear behavior of an aerated slurry-infiltrated chicken mesh beam: (a) failure mode; and
(b) load-deflection behavior.
5.3.3

Aerated Slurry-Infiltrated Chicken Mesh Columns

Figure 58 presents a typical compressive stress-deflection behavior for an aerated slurry-infiltrated
chicken mesh column. A peak stress of 15 MPa was reached, noting that loading had to be
discontinued due to deflection limitations of the test setup in the midst of an extended strainhardening behavior of the column. The column behavior in compression was highly ductile, with a
strain-hardening behavior which could be attributed to the confining effects of chicken mesh on the
66

aerated slurry (which also mobilizes the lateral tensile behavior of the chicken mesh layers restrained
by the aerated slurry). It should be noted that the aerated slurry provided only 5.4 MPa compressive
strength.

Stress, MPa

15
10
5
0
0

10

20

30

40

50

60

70

80

Deflection, mm

Figure 58. A typical compressive stress-deflection behavior of aerated slurry-infiltrated chicken mesh.
5.3.4

Aerated Slurry-Infiltrated Chicken Mesh Subcomponents

Figure 59a shows the load-deflection behavior of a subcomponent comprising an aerated slurryinfiltrated chicken mesh frame to which two aerated slurry-infiltrated chicken mesh sheets were
nailed, and was subjected to cyclic in-plane lateral loading. Figure 59b shows the lateral in-plane
load-deflection behavior of a similar frame tested alone (without any sheets nailed to it). Due to
some constraints in loading frame geometry, cyclic loading could not be applied symmetrically.
Nailing of sheets to the frame increased their lateral load-carrying capacity by more than 50%.
Frames with and without nails both exhibited ductile behavior with desired hysteretic energy
absorption capacity under lateral in-plane loading, noting that the hysteretic curves were somewhat
pinched in both cases. The frames tested here had relatively high height-to-width ratios of 1
(compared to 0.5 for the actual building). This particular geometry produced a tendency towards
tensile failure of the column at its base in lieu of plastic hinge formation in the beam(Figure 60). This
failure mode, however, did not compromise the ductility and hysteretic energy absorption capacity of
the frame and the subcomponent due to the ductile behavior of aerated slurry-infiltrated chicken

67

mesh under all loading conditions. The nails experienced some cyclic lateral deformations when the
subcomponent was subjected to cyclic in-plane loading.

(a) Frame with nailed sheets

(b) Frame without nailed sheets
Figure 59. Hysteretic in-plane behavior of aerated slurry-infiltrated chicken mesh frame with and
without nailed sheets.

68

(a) Tensile failure of a column

(b) Cyclic lateral deformations of a nail
Figure 60. Failure modes of the subcomponent comprising a frame with two sheets nailed to it.
The larger building subcomponent comprising two frames as well as interior and exterior wall and
ceiling/roof sheets nailed to it was subjected to cyclic lateral loading applied perpendicular to the
plane of frames. This building provided a desired balance of strength, ductility and hysteretic energy
absorption capacity (Figure 61). The nails joining the sheets to frames played a prominent role in
resisting lateral loads, noting that the frame has limited load-bearing capacity when lateral loads are
applied normal to their planes. The subcomponent behavior under lateral loading is shown in Figure
62. Nails kept the original wall orientation, and lateral deformations were allowing by nails deforming
laterally into the aerated slurry-infiltrated chicken mesh sheets. Effective interactions of nails with
69

chicken mesh layers explain the desired lateral load-deflection behavior of this building subcomponent.

Figure 61. Hysteretic behavior of the aerated slurry-infiltrated chicken mesh building subcomponent
comprising two frames with interior and exterior wall and ceiling/roof sheets nailed to it, and
subjected to cyclic lateral loading perpendicular to the plane of frames.

Figure 62. Failure modes of the subcomponent comprising two frames with sheets nailed to their
interior and exterior, and loading applied perpendicular to the frame planes.

70

CHAPTER 6
STRUCTURAL DESIGN OF A LIGHTWEIGHT BUILDING SYSTEM MADE WITH LOCALLY AVAILABLE
MATERIALS
6.1.

Introduction

The design loads of aerated slurry-infiltrated chicken mesh buildings were decided. The critical
factored load combinations were identified. The aerated slurry-infiltrated chicken mesh frames, wall
and roof/ceiling sheets, floor panels, and screws were designed to safely resist the governing load
combinations.
6.2.

Design Loads

Design loads were defined for the indigenous B-Hut. The live and snow loads were similar to those
used with conventional B-Huts. Dead loads were determined considering the densities and dimensions
of the indigenous building materials and components developed in the project. Relatively high seismic
load were selected, relying upon the highly ductile behavior of the indigenous building materials
developed in the project to absorb the input energy of strong earthquakes. In the short direction,
frames are responsible for resisting seismic forces. Procedures were devised for design of indigenous
(aerated slurry infiltrated chicken mesh) frames under seismic and gravity loads. Indigenous frames
were designed to meet the structural requirements without exceeding weight limits that allow for
manual installation of the indigenous B-Hut. These dimensions also suit thermal insulation of the roof
and walls.
6.2.1

Roof Loads

The roof loads were selected to match those used for conventional B-Hut design:
Live load:

20 psf

Snow Load:

42 psf

The roof-level dead load comprises masses of: (i) roof sheets that are 25.4 mm thick with 0.9 bulk
specific gravity; (ii) ceiling sheets that are 19 mm thick with 0.75 bulk specific gravity; (iii) beams that
71

are 9 in high and 4 in wide with bulk specific gravity of 0.75, with 4 ft spacing.
The contributions of various components to the roof-level mass are as follows: (i) 4.667 psf from roof
sheets; (ii) 2.925 psf from ceiling sheets; and (iii) 2.925 psf from beams. The total roof-level dead load
adds up to 10.517 psf.
The vertical component of seismic force is considered to be equal to the roof dead load times twothirds of the horizontal acceleration used in seismic design (described below).
6.2.2

Floor Loads

The floor live load used in B-Hut design is 60 psf. In order to control floor deflections (a serviceability
issue), a concept that is somewhat similar to slab-on-grade is used for floor design. Compacted sand
provides the grade upon which one layer of aerated slurry-infiltrated chicken mesh sheets will be
placed. The sand layer will be covered with a plastic sheet for sealing purposes. Considering the 1 inch
thickness for the aerated slurry infiltrated chicken mesh floor sheets of 0.9 bulk specific gravity (and
1.75 bulk specific gravity of compacted sand), the floor dead load can be calculated at 25 psf. This load
is a consideration in floor design, but does not contribute to the seismic forces applied to the building
structure.
6.2.3

Seismic Forces (Base Shear Method)

The seismic forces acting on the building were calculated following the ASCE-07 procedures. The
maximum earthquake ground motion

considered was defined by:

Ss = 3.4
S1 = 1.6
where, Ss and Sl are the spectral accelerations defining the design response spectrum.
Table 12 presents the values of Fa (short-period site coefficient) associated with a standard “firm” soil
condition used in residential building design. Fa values decrease with increasing ground motion

72

because the soil begins to dampen the ground motion as shaking intensifies. Therefore, soil can have
a moderating effect on the seismic shear loads experienced by the buildings in high seismic risk regions.
Dampening also occurs between a building foundation and soil, and thus has a moderating effect.
Table 12. Site soil amplification factor relative to acceleration (short period, firm soil).

Calculation of the seismic force is outlined below.
Site class is considered to be D (stiff soil):
Fa=1.1 & Fv=1.5
Adjusted maximum earthquake response acceleration:
SMS= (Fa)(Ss)=3.74 g
SM1=(Fv)(S1)=2.4 g
Design spectral response acceleration:
SDS= (2/3) SMS=2.5 g
SD1= (2/3) SM1=1.944 g
Calculation of the seismic response coefficient is described below.
Considering that some buildings can effectively dissipate energy from seismic ground motions through
ductile (damaging) behavior, the R factor is used to adjust the shear forces that would have been
experienced by a building exhibiting a perfectly elastic behavior without some form of ductile energy
dissipation. The concept has served a major role in standardizing the seismic design of buildings even
though it has evolved in the absence of a repeatable and generalized evaluation methodology with a
known relationship to actual building performance. Those structural building systems that can
withstand greater ductile damage and deformation without substantial loss of strength are assigned a
73

higher value of R. The R factor also reflects the differences in damping effects that are believed to be
exhibited by various structural systems. Table 13 presents some R values that are relevant to residential
construction.
Table 13. Seismic response modifier (R) values for residential construction.

The indigenous building system developed in this project, where aerated slurry-infiltrated chicken
mesh is used as structural material, exhibits a distinct ductile behavior when subjected to different
force systems (even shear). The structural system also relies upon the hysteretic behavior of screws
acting laterally against aerated slurry-infiltrated chicken mesh sheets to dissipate the seismic energy
input. The screw behavior in this mode of action is also highly ductile, with highly desired hysteretic
energy absorption capacity (in spite of the pinched nature of the hysteretic curves). Considering the
unusually high ductility and energy dissipation capacity of aerated slurry-infiltrated mesh structural
systems and their (screwed) joint, a high R value of 9 was considered in seismic design of the
indigenous building systems developed in the project.
An occupancy importance factor of I=1 was used in the indigenous B-hut design.
The value of Cs can thus be calculated as follows:
𝐶𝑠 =

𝑆𝐷𝑠
= 0.267
𝑅⁄
𝐼

The maximum seismic response coefficient is:

74

Ct=0.028, x=0.8
The fundamental period of vibration (T) can be estimated as:
Ta = Cthnx = 0.028*(10)0.8 = 0.17 sec
T = CuTa = 1.4*0.17 = 0.227 sec
The value of Cs,max can be calculated as follows:
Cs,max =

𝑆𝐷1
𝑇 (𝑅⁄
𝐼)

=

1.944
0.227∗9.37⁄1

= 0.85 g

For category II, the minimum seismic response coefficient is:
𝐶𝑠 =

0.5 𝑆1
𝑅⁄
𝐼

=

0.5∗1.944
9.37/1

= 0.104 g

Hence, Cs = Cs,max = 0.85 g
The vertical component of the design acceleration is estimated at (2/3).Cs,max = 0.566 g.
The building mass can be divided into two components concentrated at: (i) roof level, comprising roof
and ceiling sheets, strips sealing these sheets, and beams; and (ii) wall level, comprising interior and
exterior sheets, and columns. The corresponding seismic forces are thus applied at the roof level and
the mid-height of the building (Figure 63).

Figure 63. Seismic forces applied at two levels: roof and mid-height.
The seismic force applied at the top level (Ft) is 2.6 times the roof-level dead load:
Ft = 0.85 x (10.517 psf) x (18 ft) x 34 ft) = 0.85 x 6436.4 = 5,470 lb

75

The seismic force applied at mid-height (Fm) is 2.6 times the dead load associated with wall sheets and
columns. All aerated slurry-infiltrated chicken mesh sheets are assumed to have a thickness of ž in.
The bulk specific gravities of external and internal sheets are 0.9 and 0.75, respectively. The columns
of frames are 10.5 in high and 4 in wide, with a bulk specific gravity of 0.9 the total number of columns
is 18, and the internal and external sheets cover surface areas close to 800 sq ft (each). The total weight
of wall sheets and columns thus add up to 5,150 lb (wall sheets) plus 1,966 lb (columns). The seismic
force applied at mid-height (Fm) it thus:
Fm = 0.85 x (5,150 + 1,966) = 0.85x 7,116 = 6,048 lb
The above horizontal seismic forces can be applied in either the short or the long direction of the
building.
The out-of-plane seismic forces applied to interior and exterior wall sheets are as follows:
Interior Sheets: 0.85 x 2.93 = 2.49 psf
Exterior Sheets: 0.85 x 3.51 = 2.98 psf
Design of wall sheets under out-of-plane forces would be governed by above forces. The pullout
resistance of the wall sheet screws should also be adequate to resist these forces.
In the short direction, horizontal seismic forces should be resisted by the frames (Figure 64a, which
also show the wall, roof, ceiling and floor aerated slurry-infiltrated chicken mesh sheets to be screwed
to frames). The building frame overall and cross-sectional dimensions are presented in Figure 64b. The
cross-sectional dimensions were derived following trial-and-adjustment procedures which accounted
for the weak beam–strong column requirement. It should be noted that the frames were actually made
with aerated slurry-infiltrated chicken mesh prepared with an aerated slurry of 0.75 bulk specific
gravity.

76

(a) Overall view of the building frames

(b) The frame geometry and cross-sectional dimensions
Figure 64. Building frames.
6.3.

Structural Analysis and Design of Building Frames

6.3.1

Structural Analysis of Building Frames

The indigenous building comprises 9 frames, with a total of 18 columns. The maximum bending
moment generated under horizontal seismic forces at the column base can be calculated (Figure 65)
as:
M

= [Ft.h + Fm.(h/2)]/9 = [5,470 lb x 8 ft + 6,048 lb x 4 ft]/18 = (43,760 + 24,102)/18
= 3,700 lb.ft

The base shear force applied to each column can be calculated as follows:
v = (Ft + Fm)/18 = (5,470 + 6,048) / 18 = 639 lb

77

Figure 65. Deformation of a building frame subjected to horizontal seismic forces in the short
direction of the building.
The vertical component of the seismic force, estimated at two-thirds of the horizontal component,
could influence the roof (and ceiling) design. The downward component of this force plus the force of
gravity would be (0.566 + 1) x 10.517 = 16.46 psf. The upward component of this force minus the force
of gravity would be (0.566 – 1) x 10.517 = -4.56 psf. The downward out-of-plane seismic force
associated with the mass of (interior) ceiling sheets is (0.566 + 1) x 2.925 psf = 4.58 psf. This force
would govern the out-of-plane design of the ceiling sheets and their screws. The critical out-of-plan
force of (exterior) roof sheets is upward, and is equal to (0.566 – 1) x 4.667 = -2.02 psf. This pullout
resistance provided by screws should be adequate to resist this force. Design of roof sheets for out-ofplane behavior should be based on the heavier snow loads.
Snow load is larger than the vertical component of seismic force. Therefore, the maximum internal
forces developed in the building frame would result from load combinations including the snow load.
Among the factored load combinations involving snow load, that with the highest factor for snow load
governs the design for gravity loads:
U = 1.2 D + 1.6 S = 1.2 (10.517) + 1.6 (42) = 12.62 + 67.2 = 79.82 psf
Each frame has a tributary width of 4 ft. (see Figure 2a). Therefore, the factored gravity load applied
to the beam of the frame can be estimated as:
w = 4 x 79.82 = 319.28 lb/ft
78

The maximum bending moment developed in the beam under vertical loads could be estimated as:
Mu = 0.5xw.l2/12 = 0.5x319.28 x 162/12 = 3,403 lb.ft
This bending moment is less than (but close to) that produced under the horizontal component of
seismic load. Seismic forces thus provide the basis for design of the beam. The beam midspan would
develop (under snow and dead loads) a factored bending moment that is close to that developed at
the beam ends under the horizontal component of seismic load. Aerated slurry reinforced chicken
mesh would provide comparable flexural strengths at midspan and at ends. Therefore, the design for
the horizontal component of seismic load would also ensure safety under the critical (snow plus dead)
vertical load.
Structural Design of the Building Frames
The tensile and compressive strengths of aerated slurry-infiltrated chicken mesh were derived semiempirically. In tension, any direct contributions of the aerated slurry to tensile strength were neglected.
The aerated slurry, however, makes significant indirect contributions to tensile strength by restraining
the chicken mesh wires (which are partly oriented at an angle with respect to the tensile stress
orientation) from realignment to get oriented parallel with the tensile stress direction. The tensile
strength of aerated slurry-infiltrated chicken mesh was expressed as follows:
𝜎𝑇 = 𝛼𝜌𝑓𝑦
where, σT = tensile strength of the aerated slurry infiltrated chicken mesh, ρ = area ratio of the chicken
mesh wires oriented at less than 90o with respect to the tensile stress direction, fy = yield stress of the
chicken mesh wires (310 MPa), and Îą = an empirical efficiency factor which reflects partial
reorientation of a fraction of chicken mesh wires and the effectiveness of the restraining effect of the
aerated slurry matrix against reorientation of these wires along the tensile stress direction; the value

79

of Îą was found to be 0.56 based on experimental results.
In compression, the composite behavior of aerated slurry-infiltrated chicken mesh produces a
compressive strength that can be expressed as follows:
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′
where, σc = compressive strength of aerated slurry-infiltrated chicken mesh, β = efficiency factor of
chicken mesh reinforcement in compression (it was assumed to be similar to the efficiency factor of
chicken mesh in tension, that is 0.56), and Îł = efficiency factor of the aerated sully in compression,
which was surprisingly found (based on test results) to be 4.6. In other words, the aerated slurry, when
used with chicken mesh reinforcement, provides 5 times the compressive strength of plain aerated
slurry. Different factors could contribute to the rise in the compressive strength of the aerated slurry
in the presence of chicken mesh reinforcement, including: (i) the relatively low elastic modulus and
high Poisson’s ratio of the aerated slurry are expected to produce relatively large strains in
compression which are restrained by the chicken mesh reinforcement of high specific surface area and
close spacing, with the resulting confining effect raising the aerated slurry compressive strength; and
(ii) chicken mesh with high specific surface area and close wire spacing effectively reinforces chicken
mesh against restrained shrinkage microcracking. The rise in compressive strength of aerated slurry
when used with chicken mesh reinforcement is a significant factor enabling the otherwise nonstructural (insulating) aerated slurry to make structural contributions to the aerated slurry-infiltrated
chicken mesh performance.
Using concepts similar to those used with reinforced concrete, the nominal flexural strength (Mn) of
an aerated slurry-infiltrated chicken mesh cross-section (Figure 66) can be expressed as follows:
ℎ
𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)( )
2
80

where, ‘a’ is a value related to (and somewhat smaller than) the depth of neutral axis (c); a constant
compressive stress is assumed up to depth ‘a’ in order to simulate the nonlinear compressive strength
distribution up to the depth of neutral axis ‘c’. The value of ‘a’ can be derived based on the equilibrium
of the tensile and compressive forces generated at the section subjected to bending moment:
𝛼𝜌𝑓𝑦 (ℎ − 𝑎) = (𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ )𝑎

Figure 66. Cross-section and flexural strain distribution of aerated slurry-infiltrated chicken mesh.
As a first step, the expression derived above for the nominal flexural strength of aerated slurryinfiltrated chicken mesh was verified using experiments performed on a beam and a sheet made
with aerated slurry-infiltrated chicken mesh sheets and beams. These structural test specimens were
made with a slurry proportioned with saponin: water: cement at 0.00045: 0.6: 1 weight ratios (which
yielded a bulk specific gravity of 0.8 after hardening and air-drying). Twelve layers of chicken mesh
were used in the aerated slurry infiltrated chicken mesh sheet with a thickness of 20 mm. The
resulting wire area ratio at the sheet cross section was 0.02. Table 14 presents the aerated slurry
reinforced chicken mesh sheet dimensions, reinforcement conditions, test results, and the
experimental and theoretical values of flexural strength. The theoretical values of flexural strength
obtained with the expression presented above are observed to exceed experimental values by 2 to
7%. The approach outlined above for calculation of the nominal flexural strength of aerated slurryinfiltrated chicken mesh sheets and beams was thus considered to be valid.

81

Table 14. Aerated slurry infiltrated chicken mesh sheet and beam dimensions, reinforcement and
loading conditions, and test results versus predicted values.

Specimen

Sheet
Beam

# of
Chicken
Mesh
Layers
12
30

Span,
mm

Width,
mm

Thickness,
mm

Peak
Load, N

3 or 4
Point
Loading

450
800

150
102

20
254

1300
25000

4
3

Flexural
Strength, N.mm
Test

Theory

97.5
5000

94.2
5001

The aerated slurry-infiltrated chicken mesh beam and column cross-sections that meet the flexural
strength requirements (governed by seismic loads) are shown in Figure 67. There are two groups of
chicken mesh: (i) 30 layers which are placed in formwork in folded form; and (ii) four layers that are
wrapped around to mitigate the potential for split cracking upon screw application to columns and
beams. Along the height, the total number of chicken mesh layers is thus 38. Longitudinally and
transversely oriented chicken mesh layers would produce 2.58% and 0.612% area fraction,
respectively. In a later modification of the chicken mesh placement method, the mesh was formed
via rolling rather than folding. This approach produced outer layers of chicken mesh that were
parallel to the beam (and column) outer surfaces. Therefore, there was no need to have another
groups of wire mesh to wrap the interior layers.

82

Figure 67. Aerated slurry infiltrated chicken mesh beam and column cross sections in building
frames.
With longitudinally oriented chicken mesh layers, the tensile and compressive strengths of aerated
slurry- infiltrated chicken mesh beams would be:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.26𝑥0.0258𝑥310 = 2.08 𝑀𝑃𝑎 (301.7 psi)
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.26x0.0258x310 + 4.6x3.5 = 18.18 MPa (2,637 psi)
Equilibrium of tensile and compressive forces can be used to calculate the value of ‘a’ required for
calculation of the nominal flexural strength:
𝜎𝐶 . 𝑎 = 𝜎𝑇 . (ℎ − 𝑎)
2,637xa = 301.7x(9-a)
a = 0.92 in
The nominal flexural strength of the aerated slurry-infiltrated chicken mesh can now be calculated as
follows:
ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 ) = 0.26x0.0258x44,962x4x(9-0.92)x(9/2) = 44,607 lb.in

83

This nominal flexural strength of 44,607 lb.in (3,717 lb.ft) times capacity reduction factor (assumed
0.95 for the highly ductile aerated slurry-infiltrated chicken mesh) is adequate for resisting the
maximum bending moment of 3,700 lb.ft developed under the horizontal component of seismic load
and 3,403 lb.ft developed under the critical (factored snow plus dead) factored vertical load. The beam
design is thus satisfactory as far as flexural forces are concerned.
The maximum shear force developed at the base of a column under the horizontal component of
seismic load is 639 lb. The maximum shear force developed in beams under factored snow plus dead
loads is (331 lb/ft)x(16 ft) / 2 = 2,648 lb. This maximum shear force in beams produces a shear stress
of 2,648 / (4x9) = 73.6 psi. Mohr’s diagram indicates that a diagonal tensile stress of about 73.6 psi
would be developed as a result of this shear force. The tensile strength of the aerated slurry infiltrated
chicken mesh sheet (𝜎𝑇 = 𝛼𝜌𝑓𝑦 ) in the longitudinal (𝜌 = 0.0258) and transverse (𝜌 = 0.00612)
directions are 302 psi and 71 psi. An average of these two values at 45o angle would be 187 psi. The
critical tensile stress of 73.6 psi is thus significantly smaller than the nominal tensile strength (times a
capacity reduction factor relevant to shear, which would be greater than 0.8 for the highly ductile
aerated slurry infiltrated chicken mesh). The beam designed for flexure would thus behave safely in
shear.
The critical axial force in columns would develop under factored snow plus gravity loads (82.176 psf).
With a tributary width of 4 ft for each frame, this factored vertical force translates into a column axial
force pf 81.176x4x18/2 = 2,922 lb. The resultant compressive stress developed in columns would be
2,922/(4x10.5) = 69.6 psi. The nominal compressive strength of the aerated slurry infiltrated chicken
mesh column would be
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.26x0.0201x310 + 4.6x3.5 = 1.62 + 16.1 = 17.7 MPa (2,570 psi)

84

This nominal compressive strength (after application of a capacity reduction factor) would still be
significantly greater than the maximum compressive stress developed in columns. The negligible
compressive stress of columns implies that the design based on flexure is adequate.
The beam and column dimensions noted above produce a total frame weight of 389 lb (187 lb for the
beam, and 202 lb for the two columns) that allows for its manual handling and assembly. These
dimensions also provide the space required for insulation of the roof and walls.
6.3.2

Design of Roof Sheets

The aerated slurry infiltrated chicken mesh roof sheet that meet the flexural strength requirements
have a thickness of 1 inch and 12 layers of chicken mesh reinforcement, with a width of 4ft and length
of 9 ft that qualifies them as one-way slabs. The chicken mesh layers are oriented along the width of
sheets (which is the direction of their one-way action).
For a 1-ft strop of sheet (b=1 ft) and the longitudinal direction of chicken mesh oriented along the
width direction with 4 ft dimension. The tensile and compressive strengths of aerated slurry-infiltrated
chicken mesh beams in the direction of one-way action would be:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.26𝑥0.0325𝑥310 = 2.59 𝑀𝑃𝑎 (375 psi)
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.26x0.0325x310 + 4.6x5 = 2.59 + 23.0 = 25.59MPa (3,711 psi)
Equilibrium of tensile and compressive forces can be used to calculate the value of ‘a’ required for
calculation of the nominal flexural strength:
𝜎𝐶 . 𝑎 = 𝜎𝑇 . (ℎ − 𝑎)
3,711xa = 375x(1-a)
a = 0.09in
Flexural strength of the aerated slurry-infiltrated chicken mesh roof sheet can now be calculated as
follows:
85

ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 ) = 0.26x0.0325x44,962x12x(1-0.09)x(1/2) = 2074 lb.in
From ASD load Combinations and table 2, for a 1-ft width, the factored bending moment on the roof
sheet is:
Mu=ql2/8=79.82 x42/8=159 lb. ft=1907 lb.in
The nominal flexural strength of 2074 lb.in times the capacity reduction factor (assumed 0.95 for the
highly ductile aerated slurry-infiltrated chicken mesh) is equal to the maximum factored bending
moment of 1907 lb.in. The roof sheet design is thus satisfactory as far as the flexural forces are
concerned.
6.3.3

Design of the Floor Sheets as Slabs-on-Grade

The k-value used for floor slab (sheet) design reflects the response of the subgrade under temporary
(elastic) conditions and small deflections, usually 0.05 inches or less. Soil compressibility and bearing
capacity values (normally used to predict and limit differential settlements between footings or parts
of a foundation) reflect total permanent (inelastic) subgrade deformations that may be 20 to 40 (or
more) times greater than the small deflections on which k-values are based. Substantial pavement
research has shown that elastic deflections and stresses of the slab can be predicted reasonably well
when using k-value to represent the subgrade response. Consequently, the control of slab stresses
based on the subgrade k-value is a valid design procedure:
𝑘ℎ
𝑤 = 𝑠√
𝐸
where, w = the maximum allowable distributed stationary live load (60 pounds per square foot), s =
allowable extreme fiber stress in tension (psi) excluding shrinkage stresses (assumed to be equal to
one-half the normal 28-day flexural strength), ks = the modulus of subgrade reaction (150 pounds per
cubic inch for the conditions considered here), h = the slab (sheet) thickness (1 inch), E= elastic

86

modulus of the slab (572,899 psi, 3.95 GPa).
150𝑙𝑏
3 ×1𝑖𝑛
√
60 𝑝𝑠𝑓 = 0.416𝑝𝑠𝑖 = 𝑠 𝑖𝑛
572899𝑝𝑠𝑖
s = 25.7 psi
Hence, the required flexural (tensile) strength of the floor sheet is 2×s=51.4 psi.
The tensile strength provided by the aerated slurry-infiltrated chicken mesh sheet of 1 inch thickness
with 12 layers of chicken mesh reinforcement is:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.26𝑥0.0325𝑥310 = 2.59 𝑀𝑃𝑎 (375 psi)
This value (even after application of a capacity reduction factor) would be an order of magnitude
greater than the required level of tensile strength. Therefore, the floor slab (sheet) design is more
than adequate for a slab-on-grade configuration.
The flexural strength of the floor sheet with 1 inch thickness and 12 layers of chicken mesh
reinforcement is calculated below for a 1 ft strip
The aerated slurry-infiltrated chicken mesh floor sheet that meets the flexural strength requirements
with 1 inch thickness, 4ft width by 16 ft length, 12 layers chicken mesh reinforcement.
The tensile and compressive strengths of aerated slurry infiltrated chicken mesh sheets would be:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.26𝑥0.0325𝑥310 = 2.59 𝑀𝑃𝑎 (375 psi)
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.26x0.0325x310 + 4.6x5 = 2.59 + 23.0 = 25.59MPa (3,711 psi)
Equilibrium of tensile and compressive forces can be used to calculate the value of ‘a’ required for
calculation of the nominal flexural strength:
𝜎𝐶 . 𝑎 = 𝜎𝑇 . (ℎ − 𝑎)
3,711xa = 375x(1-a)

87

a = 0.09in
Flexural strength of the aerated slurry-infiltrated chicken mesh sheet can now be calculated as follows:
ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 ) = 0.26x0.0325x44,962x12x(1-0.09)x(1/2) = 2074 lb.in
In case the slab (sheet) is subjected to four-point loading on a span of 16 ft without the benefit of the
subgrade support, it can resist
4

4

F = 4𝑥𝑀𝑛 𝑥 𝐿 = 4𝑥2074𝑙𝑏. 𝑖𝑛 𝑥 16𝑓𝑡𝑥12𝑖𝑛𝑐ℎ/𝑓𝑡 = 172 𝑙𝑏dApproach for Foundation Design
6.3.4

Footing Design

Figure 68 presents a schematic depiction of an isolated footing that resists forces generated in a
column under gravity and lateral loads. The aerated slurry-infiltrated chicken mesh footing (Figure 69)
that meets the strength requirements outlined below has a thickness of 8 in, planar dimensions of 14
in x 14 in, and 30 layers of chicken mesh reinforcement.

Figure 68. Schematics of the aerated slurry-infiltrated chicken mesh footing.

Figure 69. Top view of the footing.

88

Table 15 presents the presumptive soil bearing capacities for different soil types. B-Hut is assumed to
be supported on a gravel, which provides a bearing capacity of 3,000 psf.
Table 15. Presumptive soil bearing values for different soil types.

The service loads that are transferred to the 18 isolated footings of the building are calculated below.
Floor Live load (16 ft)(32 ft)(60psf) = 30,720 lb
Floor Dead load (16 ft)(32 ft)(9psf) = 4608 lb
Footing and column dead load = 15729 lb
The minimum size of the concrete footing required to support the loads is:
The required soil bearing area =
=

𝑆𝑒𝑟𝑣𝑖𝑐𝑒 𝑙𝑜𝑎𝑑
Presumptive soil bearing capacity
(30,720+4608+15729)Ib
=17 ft2
3000 psf

The required bearing area for one isolated footing = 17 / 18 = 0.95 ft2
Since the footing has a square planar geometry, the width will be b = √0.95 = 0.97 ft = 12 in < 14 in
The soil pressure based on factored loads = qs=

𝑃𝑢
𝐴 𝑓𝑜𝑜𝑡𝑖𝑛𝑔

safe
For seismic flexural design
Seismic load E=8895 lb
1. Load= 1.4D=1.4 x4600=6,451.2lb
6,451.2lb/(142*18)inch2 =1.82psi=263.3psf

89

=

𝐷𝑙+1.6
=
17𝑓𝑡 2

2732 < 3000 psf , so the design is

2. Load =1.2D+1.6L=1.2 x4600+1.6 x30720=54,681lb
54,681lb/24.5ft2=2231psf
3. Load= 1.2D+E+L=1.2 x4600+8895+30720=45,144lb
45,144lb/24.5ft2=1842psf
4. Load=0.9D+E= 0.9 x4600+8895=13,042lb
13,042lb/24.5ft2=532.2psf
The Load case 2 controls the flexural design for footing. The factored bending moment is:
𝑙−𝑐 2
𝑀𝑢 = 𝑞𝑢 (
) (𝑏)/2
2
=2231psfx[(14inch-4inch)2/2]x14inch/2/144ft2/inch2
=1355 lb. in
With longitudinally oriented chicken mesh layers in 4 ft direction, the tensile and compressive
strengths of the aerated slurry-infiltrated chicken mesh sheet would be:
𝜎𝑇 = 𝛼𝜌𝑓𝑦 = 0.26𝑥0.009𝑥310 = 0.78 𝑀𝑃𝑎 (113 psi)
𝜎𝐶 = 𝛽𝜌𝑓𝑦 + 𝛾𝑓𝑐′ = 0.26x0.009x310 + 4.6x3.5 = 0.78 + 16.1 = 16.88 MPa (2,448 psi)
Equilibrium of tensile and compressive forces can be used to calculate the value of ‘a’ required for
calculation of the nominal flexural strength:
𝜎𝐶 . 𝑎 = 𝜎𝑇 . (ℎ − 𝑎)
2,448xa = 113x(8-a)
a = 0.35 in
Flexural strength of the aerated slurry-infiltrated chicken mesh footing cross-section can now be
calculated as follows:
ℎ

𝑀𝑛 = 𝛼𝜌𝑓𝑦 𝑏(ℎ − 𝑎)(2 ) = 0.26x0.009x44,962x14x(8-0.35)x(8/2) = 45,072 lb.in

90

This nominal flexural strength times a capacity reduction factor (assumed to be 0.95 for the highly
ductile aerated slurry-infiltrated chicken mesh) is significantly greater than the maximum bending
moment of 1,355 lb.in. The footing design is thus satisfactory as far as flexural forces are concerned,
noting that the transverse direction of chicken mesh would still provide adequate reinforcement and
thus flexural strength.
6.3.5

Design of Screws

Different screws were evaluated for use with aerated slurry-infiltrated chicken mesh. These screws
were 4 in long with 0.17 in or 0.14 in diameter, or 3 in long with 0.18 in or 0.11 in diameter.
The structural function of interior and exterior walls can be largely defined by their role in resisting
lateral (seismic) forces in the direction that is out of the plane of frames. The screws joining the wall
sheets to columns play a governing role in their design under seismic forces. The lateral seismic forces
applied to interior and exterior wall sheets are as follows:
Interior Sheets: 0.85 x 2.93 = 2.49 psf
Exterior Sheets: 0.85 x 3.51 = 2.98 psf
The screws joining the exterior wall sheets to frames were designed under seismic loading. For the inplane behavior of sheets under lateral loading, the required number of screws can be calculated as
follows (Figure 70):
n = (P.H) / (F.b)
where, P (the lateral load apply on the top of frame) is 7585 lb, F (the nail effective plateau lateral loadcarrying capacity) is 400 lb (from lateral nail resistance test), b is 16 ft, and H is 9 ft. The above equation
thus yields n=10. Hence, 10 screws would be required for joining each side of a wall sheet to a column.
The spacing between screws would be 10 in.
The pullout resistance of screws should also be adequate to resist the out-of-plane lateral force applied
91

to wall sheets by the seismic inertia. The lateral load applied to a 4ft by 8 ft, external wall sheet with 1
in thickness is 2.98psf x4ft x8ft= 95.4 lb. The pullout resistance provided by one screw is 150 lb which
is larger than the applied pullout force. Therefore, the number of screws required to join the wall
sheets to columns would be governed by in-plane behavior. In order to improve the safety of screws
design, it was decided to use 14 screws at 8 in spacing to join one side of a wall sheet to a column. The
total number of screws required for joining of the internal and external wall sheets to frames would
thus be 14 x2 x18 x 2=1008.

Figure 70. Forces transferred to nails under lateral loads applied in the plane of wall sheets.
For the roof and ceiling sheets:
Cs = Cs max = 2.6 g
The in-plane lateral force applied to a 4ftx9ft roof sheet of 1 in thickness is 2.6 x4.667psf x4ft x9ft= 437
lb, which is comparable the 400 lb lateral load-carrying capacity of a screw applied to an aerated slurryinfiltrated chicken mesh sheet of 1 in thickness with 12 layers of chicken mesh reinforcement. The
upward out-of-plane seismic force applied to a roofing sheet is (2.6-1) x4.667psf x4ft x9ft= 269 lb,
which can be can be carried by the pullout resistance of two screws, noting that each screw provides

92

150 lb pullout resistance. Therefore, the demand on the pullout action of roof screws does not govern
their design. Ceiling sheets with 4ftx8ft planar dimensions, 0.75 in thickness and 0.75 bulk specific
gravity would place even less demand on screws joining them to beams. Roof and ceiling sheets
provide for improved continuity of the building systems, and enable redistribution of forces in case
one building frame or region experiences excess inelastic deformations. These important functions
rationalize the choice of using a screw spacing of 8 in, similar to walls, for roof and ceiling sheets.

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CHAPTER 7
DURABILITY OF AERATED SLURRY-INFILTRATED CHICKEN MESH
7.1.

Introduction

Aerated slurry-infiltrated chicken mesh has been developed as a lightweight composite material for
construction of safe, affordable, sustainable and economical buildings using locally available materials
and resources. This composite material has been inspired by ferrocement, except that it is developed
to meet greater structural demands. It incorporates higher volume fractions of finer reinforcement
systems; the resulting congestion of reinforcement would require use of a highly flowable slurry to
infiltrate the closely spaced reinforcing elements (wires) of high specific surface area. Another
distinguishing feature of the new composite material involves use of aerated slurry with bulk specific
gravities less than 1. Such lightweight cementitious materials are known to offer insulating by not
structural qualities. It is the synergistic actions of the aerated slurry matrix and the fine (chicken mesh)
reinforcement that transforms the aerated slurry into a structurally viable matrix, and effectively
mobilizes the chicken mesh reinforcement qualities.
Aerated slurry-infiltrated chicken mesh offers constructability attributes which, to some extent,
approach those of wood. Its moisture and moisture and weathering resistance, on the other hand,
could approach those of concrete. These features allow for construction of the whole building,
including the exterior (roof and wall) envelope of buildings, in addition to their structural and interior
elements, with aerated slurry-infiltrated chicken mesh. In roofing and exterior wall applications,
aerated slurry-infiltrated chicken mesh would be exposed to weathering effects. The work reported
herein evaluated stability of this composite material under exposure to accelerated wetting-drying and
freezing-thawing cycles. Standard accelerated aging methods developed for use with cementitious
siding and roofing elements were used in this experimental program. The effects of accelerated aging

94

on the aerated slurry-infiltrated chicken mesh sheets were evaluated through performance of flexure
tests at different stages of aging.
7.2.

Material and Methods

Saponin was used as a foaming agent, which is extracted from plants. The aerated slurry formulation
used in this investigation comprised cement: water: saponin at 1: 0.6: 0.0005 weight ratios, which
produced a bulk density of 0.8 g/cm3 after curing and air-drying. A blend of saponin and mixing water
was subjected to high-speed mixing; the resulting foamed mixing water was then mixed with cement
in a mortar mixer. Sheet specimens of 500mmx500mm planar dimensions with 20 mm thickness and
12 layers of chicken mesh reinforcement were prepared by simply pouring the slurry on top of the
chicken mesh layers; the flowable slurry infiltrated the chicken mesh and produce composite sheets.
The sheets were moist-cured at >95% relative humidity and room temperature for 7 days, and then
air-dried at 50Âą5% relative humidity for another 7 days. Three groups of sheets were prepared; one
group were tested without exposure to accelerated aging after saturation via immersion in water at
room temperature for 48 hours. The other two groups were subjected to repeated wetting-drying
cycles and repeated freezing-thawing cycles following the procedures outline below.
ASTM C1185 and ASTM C1186 present requirements relevant to cementitious sheets used as the
exterior envelope of building systems. The roofing sheets are subjected to more severe weathering
effects than the exterior wall sheets (sidings). Therefore, the accelerated aging conditions
recommended for roofing sheets were used in this experimental work.
7.2.1. Repeated Wetting-Drying Cycles
This accelerated aging condition simulates cyclic outdoor exposures involving rainy and sunny days.
Figure 71 shows an aerated slurry-infiltrated chicken mesh sheet subjected to wetting (water spray)

95

and (radiation) heating cycles. The sheet has the orientation of a roof, and is subjected to repeated
cycles comprising four phases. These phases are: (i) water spray at a rate of 4 L/min for a period of 2 h
55 min, with a water temperature not exceeding 40°C (86°F); (ii) pause for a period of 5 min; (iii) radiant
heating to raise the specimen surface temperature to 60¹5°C for a period of 2 h and 55 min; and (iv)
pause for a period of 5 min. The specimen is inspected visually after each cycle for finding any damage
or structural alteration caused by the wetting-drying cycles; they are then subjected to flexure testing.

(a)

(b)

Figure 71. Accelerated rain-heat exposure testing of a sheet specimen: (a) water spray; (b) radiant
heating.
7.2.2. Repeated freezing-Thawing Cycles
In this accelerated aging process, the test specimens are first immersed in water at 16¹10°C for a
minimum of 48 h. They are then subjected to 50 cycles of freezing and thawing that comprise: (i)
freezing at -23¹6°C for a minimum of 1 h; (ii) thawing to reach a temperature of 16¹10°C within 24 h;
and (iii) holding for a minimum of 1 h. The freeze-thaw cycle time is 6 h. After finishing the cycles of
freezing and thawing, the specimens are saturated by immersing in water at 15°C for 48 hours, and
then subjected to flexure testing.

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7.3.

Test Results and Discussion

Exposure of aerated slurry-infiltrated chicken mesh sheets to wet-dry and freeze-thaw cycles did not
produce any visible indications of damage (Figure 72). Table 16 and Figure 73 summarize the flexural
strength test results for aerated slurry-infiltrated chicken mesh sheets in unaged condition and after
exposure to different wetting-drying and freezing-thawing cycles. Analysis of variance of test results
indicated that the effects of wetting-drying cycles on flexural strength are statistically negligible at
0.1% level of significance. The accelerated aging effects on flexural strength are relatively small, and
are not statistically significant at 5% significance level.

(a) Unaged

(b) After 100 cycles of wetting and drying

(c) After 50 cycles of freezing and thawing
Figure 72. Visual appearance of aerated slurry-infiltrated chicken mesh sheets subjected to different
accelerated aging conditions.
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Table 16. Flexural strength test results.
Accelerated Aging

Cyclic times Flexural Strength, MPa
3.58

None

0

3.64
3.66
3.18

5

3.25
3.33

Wet-Dry Cycles

3.16
50

3.22
3.28

100

3.17
3.36
3.46

15

3.33
3.49
3.45

Freeze-Thaw Cycles

2.99
50

3.11
3.23
3.08

98

Flexural Strength, MPa

4

3

2

1

0

Accelerated Aging
Freeze-Thaw
Wet-Dry
0

20

40

60

80

100

120

Number of Cycles
Figure 73. Flexural strength test results.
One potential concern with cementitious composites subjected to weathering effects relates to their
embrittlement over time. Figure 74 and Figure 75 show the effects of repeated wet-dry and freezethaw cycles, respectively, on the flexural load-deflection behavior of the aerated slurry-infiltrated
chicken mesh sheets. The ductility and energy absorption capacity (represented by the area
underneath the flexural load-deflection curves) are observed to be retained under accelerated aging
effects. Therefore, no trends towards embrittlement are observed under accelerated aging effects.

99

Figure 74. Effects of the number of wet-dry cycles on the flexural load-deflection behavior of aerated
slurry-infiltrated chicken mesh sheets.

Figure 75. Effects of the number of freeze-thaw cycles on the flexural load-deflection behavior of
aerated slurry-infiltrated chicken mesh sheets.

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CHAPTER 8
CONCLUSIONS

Aerated slurry-infiltrated chicken mesh was developed as a lightweight building material which
allows for construction of affordable, sustainable and safe building systems using locally available
materials and resources. Screws are used for joining of aerated slurry-infiltrated chicken mesh
structural components. Experimental investigations were conducted on the structural performance
of specimens, structural elements and building components and screwed joints. The durability
characteristics of aerated slurry-infiltrated chicken mesh sheets were also investigated. Structural
analysis and design methods were developed for aerated slurry-infiltrated chicken mesh building
system. A building structure was designed for full-scale construction and evaluation of its seismic
performance. The conclusions derived at different phases of the project are presented below.

8.1.

Mechanical Properties of Aerated Slurry-Infiltrated Chicken Mesh

1. The tensile behavior of aerated slurry-infiltrated chicken mesh relies upon the support
provided by chicken mesh against realignment of the chicken mesh wires. This interaction
depends on the quality (bearing capacity, elastic modulus and compressive strength) of the
aerated slurry, and the concentration of chicken mesh as well as the specific surface area and
the spacing of chicken mesh wires.
2. Slurry-infiltrated chicken mesh sheets exhibit a ductile behavior in tension. The transition from
normal-density (non-aerated) slurry to aerated slurries of lower densities produces some drop
in peak tensile load, but not in their ductile tensile load-deflection behavior. The tensile loadcarrying capacity of aerated slurry-infiltrated chicken mesh does not increase proportionally

101

with the increasing number of chicken mesh layers per for the same sheet thickness. This is
because it is the interaction between the chicken mesh with the aerated slurry that decides
the ability to mobilize the chicken mesh load-bearing capacity within structurally viable
deformations.
3. The aerated slurry-infiltrated chicken mesh sheets exhibit a distributed failure mode marked
by crushing of the aerated slurry over a major fraction of the sheet volume. The crushing of
aerated slurry when the aerated slurry-infiltrated chicken mesh sheet is subjected to tension
further highlights the demand imposed by the tendency towards realignment of the chicken
mesh wires under tension on the mechanical qualities of the aerated slurry.
4. The flexural load-deformation behavior of aerated slurry-infiltrated chicken mesh sheets was
found to be exhibit qualitative similarities with their tensile behavior. The observations
summarized above for tensile behavior also applies to flexural behavior.
5. The flexural failure mode of aerated slurry-infiltrated chicken mesh sheets is dominated by a
single crack, and does not exhibit the distributed failure mode observed in tension. In spite of
this, the flexural failure is still highly ductile. In the case of the selected aerated slurry with 0.8
g/cm3 density, aerated slurry-infiltrated chicken mesh sheets with about 20 mm thickness
would require about 12 layers of chicken mesh in order to reach viable levels of flexural
strength.

8.2.

Screw and Nail Behavior in Aerated Slurry-Infiltrated Chicken Mesh

6. An experimental investigation was conducted on the pullout behavior of screws or nails of
different lengths and diameters from aerated slurry-infiltrated chicken mesh sheets of

102

different densities. An aerated slurry with maximum bulk density of 0.9 g/cm3 could be nailed
rather conveniently; a minimum nail diameter of 3-4 mm was found to be necessary in order
to avoid buckling of the nail during application. The pullout behavior of nails and screws from
aerated slurry-infiltrated chicken mesh sheets was ductile, and was not influenced consistently
by the nail length and diameter within the narrow ranges of these variables considered in this
investigation.
7. The number of chicken mesh layers in aerated slurry-infiltrated chicken mesh sheets had
relatively small effects on the nail and screw pullout behavior. The bulk density of the aerated
slurry, on the other hand, had notable effects on pullout behavior.
8. Screw or nail applied to aerated slurry-infiltrated chicken mesh sheets exhibit a highly ductile
behavior with relatively high load-bearing capacity under monotonic lateral loads. This critical
aspect of screw or nail behavior, which is relied upon in the indigenous building structure for
dissipation of seismic energy input, was found to engage the chicken mesh layers. As the screw
or nail lateral loading caused bearing failure of the aerated slurry, it started to engage and drag
the chicken mesh layers; the pullout resistance of the chicken mesh embedded in aerated
slurry was responsible for the relatively high lateral load-bearing capacity and the ductile
behavior of screw or nail.
9. Cyclic lateral loading of screw or nail applied to aerated slurry-infiltrated chicken mesh sheets
produced a pinched but stable hysteretic behavior with desired energy dissipation capacity.
This was again attributed to the engagement of chicken mesh layers under cyclic lateral loading.
The alignment of multiple screws or nails with respect to the loading direction was found to
be an important factor influencing the hysteretic behavior under cyclic lateral loads. Alignment

103

of screws or nails perpendicular to the loading direction, which is relevant to the indigenous
building systems considered here, produced a higher energy dissipation capacity by improving
the stability of hysteretic curves produced at a constant deflection amplitude.

8.3.

Behavior of a Lightweight Frame Made with Aerated Slurry-Infiltrated Chicken Mesh Under
Cyclic Lateral Loading

10. An aerated slurry-infiltrated chicken mesh frame with column and beam cross-section
comparable to those required for a single-story building design were subjected to cyclic lateral
in-plane loading. The frame columns were fixed inside an aerated slurry-infiltrated chicken
mesh footing. The frame failed by forming plastic hinges in beams near beam-column joints,
which is compatible with the weak beam-strong column design of the frame.
11. The aerated slurry-infiltrated chicken mesh frame exhibited a ductile failure mode with a stable
hysteretic behavior that provided significant energy absorption capacity.
12. The lateral load-bearing resistance, ductility and hysteretic energy absorption capacity of the
aerated slurry-infiltrated chicken mesh frame were found to be favorable when compared with
lateral load-resisting systems based on OSB and hardwood sheets.
13. The desired seismic performance of the aerated slurry-infiltrated chicken mesh frame can be
attributed to the high specific surface area of chicken mesh, its desired mechanical interlocking
within the cementitious matrix, its dual role as flexural and shear reinforcement, and the
confining effects of the highly distributed chicken mesh reinforcement on the aerated slurry

104

matrix.

8.4.

Structural Evaluation of a Lightweight Building System Made with Locally Available Materials

14. Aerated slurry-infiltrated sheets exhibit a ductile behavior under out-of-plane loading, which
involves a somewhat distributed failure region.
15. Aerated slurry-infiltrated chicken mesh beams exhibited a highly ductile failure involving
multiple cracking along an extended fraction of the beam length. The multiple cracks were
spaced closely, and the aerated slurry within the failed region exhibited signs of both
cracking and crushing, which could have been caused by the bearing action of the chicken
mesh wires against the aerated slurry. Reversed loading of a beam after initial failure in the
original direction produced a highly ductile behavior with a peak load that approached that
in the original loading direction. This finding provides an initial indication of the desired
hysteretic behavior of aerated slurry-infiltrated chicken mesh beams under cyclic loading.
16. Aerated slurry-infiltrated chicken mesh beams provided distinctly high levels of shear
strength complemented with a ductile behavior in shear. These findings were explained by
the dual role of flexural reinforcement that is distributed across the beam thickness as shear
reinforcement, and also the highly ductile tensile behavior of aerated slurry-infiltrated
chicken mesh. The high specific surface are of the chicken mesh reinforcement also benefits
its dowel action against the aerated slurry.
17. Structural subcomponents comprising an aerated slurry-infiltrated chicken mesh frame to
which aerated slurry-infiltrated chicken mesh sheets were nailed were tested under in-plane
cyclic lateral loading. A frame without any sheets attached to it was also tested under similar

105

loading. Nailing of sheets increased the lateral load-bearing capacity of the frame by more
than 50%. Both the frame tested alone and that tested with sheets nailed to it exhibited
ductile behavior with desired energy dissipation capacity, with the hysteretic curves
exhibiting a somewhat pinched attribute.
18. A structural subcomponent comprising two aerated slurry-infiltrated chicken mesh frames to
which interior/exterior wall and ceiling/roof sheets were nailed was subjected to out-ofplane cyclic lateral loading. The behavior of this frame was governed by the bearing action of
nails against the aerated slurry-infiltrated chicken mesh sheets. This subcomponent also
provided a desired balance of strength, ductility and hysteretic energy absorption capacity,
which could be attributed to the restraining effects of the chicken mesh layers against lateral
movement of nails against aerated slurry-infiltrated chicken mesh sheets.

8.5.

Structural Design of a Lightweight Building System Made with Locally Available Materials

19. The loads governing structural design of indigenous aerated slurry-infiltrated chicken mesh BHuts were defined. Structural analyses were conducted in order to calculate the internal forces
developed in different structural elements and (screwed) joints. The aerated slurry-infiltrated
chicken mesh frames and (wall, roof/ceiling and floor sheets), and screws joining different
sheets to frame elements were designed under the governing load combinations.
20. The aerated slurry-infiltrated chicken mesh structural frames and sheets designed for the
building system had reasonable weights for manual handling and installation, noting that
these elements tend to be somewhat heavier than the corresponding wood elements.

106

8.6.

Durability Characteristics of Aerated Slurry-Infiltrated Chicken Mesh

21. Aerated slurry-infiltrated chicken mesh sheets provided stable behavior under two standard
accelerated aging conditions designed for exterior cementitious roofing and siding building
products. These accelerated aging conditions involved exposure to repeated cycles of wettingdrying and freezing-thawing. The flexural strength, ductility and energy absorption capacity of
aerated slurry-infiltrated chicken mesh sheets were found to be stable under these accelerated
aging conditions.

107

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