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I 1 11.11" ' - . i 1 1.1 . 1 1 11‘11| .111 ‘11'111 .111‘ 1 . .111 1111111 11111111 1111111 111111111 11111111111 ..' “1" 1. 1.. 1 1‘1‘ 1' "1111‘...;1 111 III 1 1'1 11|1111 11 11...:1‘ 111: '.1 ' 1 1"1'1 11.11111'111 1111 .1 1111111 ‘ 11111111111 1 1111111111 11111111 I 111111111111111111111111”111111111111111111111111 111 - 1. '1'.1"1:11‘111'111|111.11 1111111111111111111111111111111111111117111111?;t .1 111111111 1 1 _ 1.11 1.11 I 11. 1111.11 ‘111111 ' .. :1 .. .‘111111'11‘.:11.'.H ' 1.1111111| 1111 111 1| 11111111.. '.‘.I 1 11.11111.1111111111111 ‘1‘ " .311 wr‘ an n... .. 4. _ 1 - name (3 L 18 R A R Y Michigan State L University f. This is to certify that the thesis entitled The Effects of Mix Design on the Design of the Pavement Structure when Utilizing Recycled Portland Cement Concrete as Aggregate presented by James S. Fergus has been accepted towards fulfillment of the requirements for Ph.D. degreein Civil Engineering 0-7639 OVERDUE FINES: 25¢ per day per item RETURNING LIBRARY MATERIALS: Place in book neturn to remove charge from circulation records AUG :32 a 392 2” gm“ MAY‘1 0 199,3, .32. THE EFFECTS OF MIX DESIGN ON THE DESIGN OF THE PAVEMENT STRUCTURE WHEN UTILIZING RECYCLED PORTLAND CEMENT CONCRETE AS AGGREGATE by James Stanley Fergus, P.E. A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Civil Engineering 1980 - -A‘-'.:.' ABSTRACT THE EFFECTS OF MIX DESIGN ON THE DESIGN OF THE PAVEMENT STRUCTURE WHEN UTILIZING RECYCLED PORTLAND CEMENT CONCRETE AS AGGREGATE by James Stanley Fergus, P.E. The principal purpose of this research was to investi- gate the feasibility of crushing an existing Portland cement concrete pavement and using the resulting aggre- gate in the concrete mixture required for replacement of the structure. In addition, the research included initial experiments to determine the effects of incorporating bitu- minous overlay materials as a proportion of the aggregate. Many areas in this country are experiencing difficulty obtaining quality aggregates for paving and other construc- tion. Since there are a number of crushing operations engaged in crushing concrete for non-structural construction purposes, a few researchers have attempted to determine the value of this waste material for use as concrete aggregate. Each investigator predicted lower concrete strengths and, therefore, more expense when using recycled Portland cement concrete for the aggregate in a concrete mixture. Because these experiments were limited in scope, it was suggested _Tfll'_ I James Stanley Fergus, P.E. that further research would be necessary before a valid determination could be made. The experimental procedures used for this research attempted to incorporate the complete range of variables found in crushing and utilizing recycled concrete including determinations of crushing properties, aggregate properties, and concrete properties with varying mix proportions. Re- search results were applied to the economic, environmental, and design factors related to Portland cement concrete pavement construction. The basic research procedure was to obtain sufficient amounts of concrete from an existing pavement to perform comprehensive experiments. Material for the standard experiments was obtained from pavement slab sections which had been removed from a highway during a reconstruction project. The slab material was crushed at a commercial crushing plant with further processing at the laboratory. In addition, pavement cores were obtained from various highway locations for correlation experiments. Seventy experimental tests related to the determina- tion of aggregate properties were completed. Three hundred- eighty tests were completed for the determination of con- crete properties. All laboratory tests were accomplished according to current ASTM standards or procedures used by the Michigan Department of Transportation. Pavement design was based on procedures suggested by the AASHO Interim Guide for the Design of Pavement Structures. James Stanley Fergus, P.E. The major finding of this study was that crushing existing Portland cement concrete pavements will provide an aggregate that can be used on a design basis equal to a concrete design utilizing conventional aggregates. In addition, the utilization of recycled Portland cement con- crete aggregates in new concrete provides an economically and environmentally sound resource for the reconstruction of roadways. To my wife Joan, and to my children, Carol, Deborah, Barbara, James, Christopher, Susan, David, Paul, Elizabeth, Alexander, and Laura. ACKNOWLEDGMENTS In appreciation to my guidance committee, Dr. G. C. Blomquist, Dr. J. D. Brogan, Mr. W. J. MacCreery, Dr. F. X. McKelvey, and Dr. W. C. Taylor. In special gratitude to my colleagues at the Michigan Department of Transportation for their help and encourage- ment throughout the period of this research. This research was made possible through the sponsor- ship of the Michigan Department of Transportation and a fellowship from the National Highway Institute, Federal Highway Administration. iii TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES Chapter I. INTRODUCTION. II. LITERATURE REVIEW 2.1 Physical Properties of Recycled PCC Aggregates . . . . 2.1.1 Gradation . . . 2.1.2 Absorption and specific Gravity 2.1.3 Durability Factor . . 2.2 Physical Properties of Concrete Made with Recycled PCC Aggregate . . . . . . . 2.2.1 Flexural Strength . 2.2.2 Compressive Strength. . 2.2.3 Other Physical Properties of Hardened Concrete . . . 2.3 Economics of Crushing PCC for New Pavements 2.3.1 Previous Economic Evaluations . 2.4 Concrete Mix Design. 2.4.1 Portland Cement Association Method. 2.4.2 American Concrete Institute Method. 2.4.3 Michigan Department of Transporta- tion (Mortar Voids) Method. 2.4.4 Mix Design Utilizing Recycled PCC . Aggregate . 2.5 Rigid Pavement Design. 2.5.1 Theoretical Stress Analysis . . . . 2.5.2 Portland Cement Association Method. 2.5.3 AASHO Interim Guide Method. iv, Page vii xii 14 l4 14 17 22 22 28 28 32 4O 43 45 45 48 Chapter III. IV. RESEARCH MATERIALS AND MIX DESIGN . 3.1 Component Materials. 3.1.l Materials for Recycling . 3.1.2 Bituminous Material . 3.1.3 Fine Aggregate. 3.1.4 Coarse Control Aggregate. 3.1.5 Cement. . . . . . . 3.2 Concrete Mix Design Used for Research. 3.2.1 Mix Design Procedure. AGGREGATE PROPERTIES. 4.1 Material Preparation and Gradation . 4.1.1 Field Crushed PCC Slab Sections . PCC Pavement Cores. Laboratory PCC Test Beams : Other Research Aggregates . b-I-‘L‘ rahud DOOM 4.2 Physical Properties of Research Aggregates 4.2.1 Deleterious Particles in Coarse Aggregate . . . . 4.2.2 Bulk Specific Gravity and Percent Absorption of Coarse Aggregate. 4.2.3 Salt Content (NaCl) of Portland Cement Concrete . . . 4.2.4 Experimental Results for Aggregate PrOperties. . . . . . . . CONCRETE PROPERTIES . 5.1 Aggregate Proportions for Experimental Mixes. . . . . . 5.1.1 Recycled PCC Aggregate. . . 5.1.2 Recycled PCC in Combination with Bituminous Concrete . . . . 5.2 Laboratory Procedures for Test Batches . 5. L 1 Material Weighing and Preparation . 5. L 2 Research Mix Design . . 5.2.3 Mixing Experimental Batches Page 85 89 91 91 97 98 98 99 102 102 103 104 Chapter 5.3 5.4 Properties of Fresh Concrete . 5.3.1 Workability . . . 5.3.2 Test Results for Fresh Concrete . Properties of Hardened Concrete. 5.4.1 Curing Test Specimens . . . 5.4.2 Com ressive (f') and Flexural mg Strengthsc . . . . . 5.4.3 Sonic Testing . VI. APPLICATION OF EXPERIMENTAL RESULTS . 6.1 6.2 6.3 Economic EValuation. 6.1.1 Crushing PCC for Aggregate. 6.1.2 Cost Comparisons. . . Environmental Considerations 6.2.1 Energy Requirements 6.2.2 Natural Resources . Pavement Design. 6.3.1 Concrete Properties Related to Pavement Design . . . . 6.3.2 Thickness Design Criteria . . 6.3.3 Alternate Working Stress (ft) Determination . . VII SUMMARY AND CONCLUSIONS. 7.1 Discussion of Experimental Results. 7.2 Conclusions LIST OF REFERENCES. APPENDICES: Appendix.A values Used for Economic and Energy Comparisons. Appendix B Sample Calculations . Appendix C Sample Worksheets for Experi- mental Tests. vi Page 104 104 106 106 106 111 116 122 122 123 123 126 129 129 131 131 131 132 135 135 137 139 . 143 146 . 150 Table 2-2. 2-3. 2-4. 2-5. 2-7. 2-8. 2-10. 2-11. 2-12. 2-13. LIST OF TABLES Iowa Gradation Test Results for Recycled Aggregate . Recalculated Iowa Gradation Test Results for Recycled Aggregate. Specific Gravities and Absorptions of Aggregates. Specific Gravities of Recycled Concrete From the Iowa Project . Durability Factor for Concrete Beams in Accelerated Freezing and Thawing. Selected Physical Properties of the Five Concrete Mixtures Tested. . . . Iowa Durability Factors. Iowa Project Mix Proportions 28-Day Flexural Strength Test Results from the Iowa Experimental Project . . Average Compressive Strengths of the Five Concrete Mixtures Tested. Relationship Between Water-Cement Ratio and Compressive Strength. Cement: Portland Cement Type III; Fine Aggregate: Ottawa Sand. Tested at 8 Days . . . . . . Relationship Between Water-Cement Ratio and Compressive Strength. Cement: Portland Cement Type I; Fine Aggregate: Granite Sand. Tested at 15 Days. . . . 28-Day Compressive Strength Test Results form the Iowa Experimental Project. vii Page 10 10 12 12 13 15 16 18 19 19 20 Table 2-14. 2-15. 2-16. 2-17. 2-18. 2-19. 2-20. 2-21. 2-22. 2-23. 2-24. 2-25. 3-1. 3-2. 3-3. 4-1. 4-2. Compared Compressive Strengths from.Three Studies . Linear Coefficient of Thermal Expansion of the Five Concrete Mixtures Tested. Length Changes of Concrete Specimens Stored at Constant Mbisture and Temperature. Energy Requirements for Recycled PCC Aggregate Compared to Conventional Aggregate. Recommended Slumps for Various Types of Construction. . . . . . . . . Approximate Mixing Water and Air Content Requirements for Different Slumps and Nominal Maximum Sizes of Aggregates . Relationships Between Water-Cement Ratio and Compressive Strength of Concrete. Maximum.Permissible Water-Cement Ratios for Concrete in Severe Exposures. Volume of Coarse Aggregate Per Unit of Volume of Concrete. . First Estimate of Weight of Fresh Concrete . Concrete Preportioning Data for Slipform Pavement. . . . . . Stress Ratios and Allowable Load Repetitions . Gradation Requirements for Coarse Aggregates Used in Source Material for Recycling . Gradation Requirements for Coarse Aggregates Used in Source Material for Recycling . Histories of Source Materials From Michigan Department of Transportation Road Logs . . . . . . . . . . . Crusher Run Gradations for Recycled I-96 Slab Sections . Coarse Fraction Gradation Test Results for Three Samples of Recycled PCC Aggregate A - Cumulative Percent Passing. . . viii Page 20 21 23 27 33 34 35' 36 37 38 44 51 60 60 61 71 74 Table Page 4-3. Fine Fraction Gradation Test Results for Three Samples of Recycled PCC Aggregate A - Cumulative Percent Passing. . . . . . . 75 4-4. Average Compressive Strengths of FCC Pavement Cores from Various Locations . . . 77 4-5. Gradations of Coarse Recycled PCC Aggregates - Cumulative Percent Passing. . . . . . . 79 4-6. Gradations of Fine Recycled PCC Aggregates - Cumulative Percent Passing. . . . . . . 80 4-7. Gradations of Various Coarse Aggregates Used for Research - Cumulative Percent Passing . 83 4-8. Gradations of Various Fine Aggregates Used for Research - Cumulative Percent Passing . . . 84 4-9. Michigan Gradation Limits for Coarse Aggregates Used in PCC Mixes for Pavement - Cumulative Percent Passing . . . . . . . . . . . . . . 86 4-10. Michigan Gradation Limits for Fine Aggregates Used in Mixes for PCC Pavements - Cumulative Percent Passing . . . . . . . . . . . . . . 87 4-11. Coding and Source Information for Research Aggregates. . . . . . . . . . . . . . . . . 88 4-12. Weighted Bulk Specific Gravity (Gb ) and Percent Absorption (AA) of Recycled PCC Coarse Aggregate 90 4-13. Salt Content (NaCl) of Recycled PCC Aggregate . . . . . . . . . . . 92 4-14. Deleterious Particles in Coarse Aggregates Used for Research Compared to Michigan Department of Transportation Specifications 93 4-15. Various Properties of Coarse Aggregates Used for Research. . . . . . . . . . . . . . . 94 4-16. Various Properties of Fine Aggregates Used for Research. . . . . . . . . . . . . . . 95 5-1. Combinations of Aggregates Used for Recycled PCC Mix Design. . . . . . . . . . . . . . . 100 ix Table 5-3. 5-4. 5-5. 5-6. 5-8. '5-9. 5-10. 5-11. 6-1. 6-2. 6-4. Combinations of Aggregate Used for Recycled PCC Mix Design Including Bituminous Concrete. . . . Average Percent Retained on Each Sieve Size For Aggregate A . Properties of Fresh Concrete Made with Recycled PCC Aggregate. . . . Properties of Fresh Concrete Made with Combinations of Recycled PCC and Crushed Bituminous Concrete . Air Contents of Concrete Made with Proportions of Recycled PCC and Bituminous Concrete . Number of Test Specimens Made for Each Experimental Batch. Compressive and Flexural Strengths of Concrete Made with Recycled PCC and Control Aggregate . . . . . . . Compressive and Flexural Strengths of Concrete Made with a Combination of Recycled PCC and Bituminous Concrete. Durability Factors (DF)* for Research Mixes. Dynamic Young's Modulus of Elasticity (E) and Poisson's Ratio (u) for Selected Research Test Specimens . . . . Estimated Hourly Costs for a Recycled PCC Crushing Operation. . . . . . Aggregate Proportions Using Recycled PCC or Natural Aggregate for One Cubic Yard of Concrete - Based on Replacing an Equal Section . . . . . . . . . Cost Comparisons for Aggregate Alternatives for a Ten Mile Dual PCC Pavement Removal and Replacement Project - Based on 1979 Michigan Prices . Energy Requirements for Aggregate Alternatives for a Ten Mile Dual PCC Pavement Removal and Replacement Project . Page 101 103 107 108 109 109 112 113 . 119 121 125 127 . 128 . 130 Table A Page 6-5. Pavement Thickness Design Based on Standard Research Mix Designs . . . . . . . . . . . . 133 6-6. Alternate Determinations of Working Stress for Research Mixes . . . . . . . . . . . . . 134 xi Figure 2-1. 2-2. 2-3. 2-4. 2-5. 2-6. 2-7. 2-8. 2-9. 2-10. 2-11. 2-12. 3-1. 3-2. 3-3. 3-4. LIST OF FIGURES Relationship Between Water-Cement Ratio and Medulus of Elasticity. Cement: Portland Cement Type III; Fine Aggregate: Ottawa Sand. . . . . Relationship Between Water-Cement Ratio and Modulus of Elasticity. Cement: Portland Cement Type I, Fine Aggregate. Granite Sand. . . . . . . Schematic Flow Chart of Recycling Plant. Typical Trial Mix Strength Curves. Typical Relationship Between Percentage of Fine Aggregate and Cement Content for a Given Water-Cement Ratio and Slump. Typical Curve Showing the Relationship Between the Water Content of Mortars and the Volume of Mortar . Typical Relationship Between Compressive Strength and Cement-Space Ratio . Westergaard's Case for Corner Loading. Design Chart for Single-Axle Truck Loads Design Chart for Tandem-Axle Truck Loads Design Chart for Rigid Pavements, Pt = 2.5 . Design Chart for Rigid Pavements, Pt = 2.0 . Typical Transverse Joint Failure . Removal of Slab Sections for Joint Repair. Disposal Site for Waste Pavement Sections. Breaking Pavement Slabs for Research Material. Goring Pavement Slabs. xii Page 24 24 26 30 31 41 42 46 49 50 52 53 57 57 58 58 59 Figure Page 3-6. Charging Apron Feeder at Michigan Crushed 63 Concrete, Inc. . . . . 3-7. Hand-Picking Steel and Other Material from Crusher Belt at Michigan Crushed Concrete Inc. . . . . . . . . . . . . . . . 63 3-8. Removal of Steel from Crusher Belt by Magnet at Michigan Crushed Concrete, Inc.. . . . . 64 4-1. Gilson Mechanical Grader . . . . . . . . . . . 73 4—2. Denver Jaw Crusher . . . . . . . . . . . . . . 73 4-3. Particle Size Distribution of Coarse and Fine Fractions of Aggragate A . . . . . . . 76 4—4. Particle Size Distribution of Coarse and Fine Fractions of Recycled PCC Aggregates . 81 5-1. Laboratory Pan Mixer . . . . . . . . . . . . . 105 5-2. Roll-A-Meter for Volumetric Air Tests. . . . . 105 5-3. Air Contents of Concrete, Containing Propor- tions of Crushed Bituminous Concrete for Aggregate with the Addition of Various Amounts of Air Entraining Admixture . . . . 110 5-4. The Effects of the Percent of Recycled PCC Fine Aggregate, in Total Fine Aggregate, on Compressive Strength . . . . . 114 5-5. The Effects of the Percent of Recycled PCC Fine Aggregate, in Total Fine Aggregate, on Flexural Strength. . . . . . . 115 5-6. Soiltest CT 366C Sonometer . . . . . . . . . . 117 5-7. Freeze- Thaw Chamber. . . . . . . . . . . . . . 117 6-1. Schematic of a Portable Recycled PCC Crushing Operation. . . . . . . . . 124 xiii CHAPTER I INTRODUCTION Due to the extensive road building and other construc- tion programs carried on in the United States since the 1950's, the availability of quality aggregates for construc- tion purposes has become critical in many geographical areas. This shortage of aggregates has led to a variety of experi- mental projects using "waste" or recycled materials for all or part of the components of roadway structures. To date, most work involving recycled materials for highways has concentrated on using these materials in bituminous con- crete mixtures and for base course materials. until the early 1970's, most Portland cement concrete waste materials were disposed of in landfills, but problems with meeting the requirements of new environmental restric- tions is making this procedure more difficult. In addition, it is not unusual to have to haul great distances to suit- able landfill sites when this waste material is generated in urban areas. Therefore, economic factors have led to the establishment of major waste Portland cement concrete crushing operations in many metropolitan areas which have proven to be both environmentally and economically feasible. Most of the material resulting from these crushing opera- tions is used as subbase for road and parking lot surfacing, aggregate driveways, and various fill purposes. An investi- gation of crushing operations in the Detroit, Michigan metropolitan area indicated that appropriate screening could produce an aggregate with a gradation suitable for concrete mixtures at a cost which would be competitive with other natural or manufactured aggregate. Many of the highway systems started in the late 1950's using Portland cement concrete for the surface structure are now in the need of repair. This is normally accomplished by some bituminous overlayment procedure. An investigation of highway systems in Michigan resulted in a determination that these overlays normally have a useful service life of about eight years. Therefore, it would seem desirable to completely rebuild the surface structure for a service life of twenty years or more if reduced periods of traffic con- trol and maintenance are a consideration. In addition, a limited amount of overlays can be placed on existing roadways due to the necessity of maintaining overhead clearance at structures. Furthermore, complete removal of an existing pavement for the purpose of recycling the materials into a new pavement would allow for correction of subgrade failures, deficiencies in geometrics, and drainage problems. Before a roadway has been selected for recycling into a new pavement structure, it would be preferable to have some knowledge of the physical properties of the final mixture 3 with regard to design. The limited data available, to date, indicated the possibility of having to design thicker pave- ments with recycled concrete materials, in addition to other construction and material problems. A determination that it may not be possible to use all of the material available in the existing pavement for the new concrete mixture on an equivalent design basis would be very important from an economical and processing standpoint. The main emphasis of this research was to investigate the variables connected with completely recycling existing Portland cement concrete pavement materials and to apply the results to the design of Portland cement concrete pave- ment. Although theoretical concepts with respect to pave- ment design will be discussed, the final application of research results will be based on empirical determinations. CHAPTER II LITERATURE REVIEW Although the use of building rubble as aggregate for concrete construction purposes was reported in Europe imme- diately following World War II (4,13), technical data was somewhat limited. Reported construction projects in the United States which utilized recycled concrete as an aggre- gate substitute for new Portland cement concrete are re- stricted to a few airfield reconstruction projects (18,24, 25) and an experimental paving project in Iowa (3). Since the concrete mixtures for the airfields were actually "lean mixes" used as subbase for conventional concrete surfacing, the results are not pertinent to this study. The technical report concerning the Iowa project offered valuable back- ground information for pavement and concrete mix design. However, conclusions resulting from this project, in addi- tion to other studies (4,12) indicated a need for further research. This was particularly true in the design of the thickness of the surfacing structure, the utilization of bituminous overlayment materials, and the incorporation of crusher fines in a concrete mixture. In addition, previously reported research did not thoroughly investigate the physical properties of materials resulting from.concrete crushing Operations with respect to gradation characteristics, structural integrity, and mix design incorporating the number of variables which result from crushing operations. Furthermore, a review of exist- ing literature did not produce a valid analysis of the economic and environmental factors applicable to the utili- zation of aggregates produced by crushing existing Portland cement concrete (PCC) pavements and using this material in concrete produced for the replacement structure. 2.1 Physical Properties of Recycled PCC Aggregates There exists a traditional theory which states that the final concrete product is no better than the aggregates used in the mix. Therefore, this section will concentrate on previous research related to the basic qualities of re- cycled PCC aggregates. 2.1.1 Gradation The gradation or grain size distribution of aggregates is an important property affecting the strength and propor- tions of a concrete mixture (42). Most conventional aggre- gates such as gravel and crushed stone are produced through a crushing and/or screening process that assures a gradation falling within certain specified limits. However, the assur- ance of a consistant gradation is the most important factor from a concrete mix design standpoint. The Iowa report (3) was the only study that offered an indication of the overall crushing characteristics of re- cycled PCC under field conditions. In this case, an exist- ing PCC pavement, resurfaced with three inches of asphalt concrete, was selected for an experimental project. The asphalt was removed as a separate operation prior to pave- ment breaking and removal. The asphalt and Portland cement concrete materials were independently crushed in a primary jaw crusher to a minus six inch size and stockpiled. The materials were then processed through a secondary crusher to 100 percent passing the l-l/2 inch size screen opening. Since it was intended to use a combination of asphalt and Portland cement concrete in part of the project, a portion of the six inch top size material was passed through the secondary crusher in approximately the same proportions existing in the original pavement. A laboratory analysis of gradations of the crushed PCC alone and the combination of materials (Table 2-1) indicated a fairly well-graded material. The analysis did not indi- cate whether the asphalt concrete crushed linearly with the PCC concrete when the materials were crushed together. In- formation of this nature would have been of significant value for design purposes. Reported field observations on the Iowa (3) project were that there was a high degree of segregation of aggre- gate particle sizes when stockpiling the material from the Table 2-1. Iowa Gradation Test Results for Recycled Aggregate. (Source: Bergren and Britson)(3) Crushed PCC Crushed PCC and AC Sieve Z Retained Z Passing Z Retained Z Passing 1" 10.1 89.9 15.0 85.0 3/4" 18.6 71.3 17.0 68.0 1/2" 23.4 47.9 21.7 46.3 3/8" 8.6 39.3 8.5 37.8 #4 16.0 23.3 15.9 21.9 #8 7.6 15.7 7.8 14.1 #16 4.4 11.3 4.2 9.9 #30 3.7 7.6 3.7 6.2 #50 3.5 4.1 3.0 3.2 #100 1.9 2.2 1.4 1.8 #200 1.0 1.2 0.8 1.0 Pan 1.2 1.0 .100.0 100.0 secondary crusher. This generated abnormal batching diffi- culties when the materials were used. Therefore, final recommendations resulting from research experience on this (project were that the crushed materials should have been separated by appropriate screening into fine and coarse fractions and stockpiled separately. This can be accom- plished through a simplified crushing Operation as indicat- ed by previous work in Florida (23,25). The gradations shown in Table 2-1 were recalculated to provide information concerning the fine and coarse aggregate particle sizes using material retained on the #4 sieve as the size split (Table 2-2). 2.1.2 Absorption and Specific Gravity A determination of the absorptions and specific gravi- ties of component materials is necessary for concrete mix design purposes. Buck (4), in his work at the United States Army Engineer Waterways Experiment Station reported values listed in Table 2-3. The first values listed were for crushed material from a driveway containing siliceous aggre- gate (chert gravel and natural sand) in the PCC mix. The second material was from a laboratory beam containing cal- careous coarse aggregate (limestone) and a siliceous natural sand. Test results for control aggregates are also included. Specific gravity results, only, were furnished in the Iowa(3) report (Table 2-4). The original concrete used for recycling was made with natural gravel coarse aggregate Table 2-2. Recalculated Iowa Gradation Test Results for Recycled Aggregate. (Based on Bergren and Britson)(3) Crushed PCC‘ Crushed PCC and AC Sieve Z Retained Z Passing Z Retained Z Passing Coarse Fraction 1" 13.2 86.8 19.3 80.7 3/4" 24.2 62.6 21.9 58.8 1/2" 30.5 32.1 27.9 30.9 3/8" 11.2 10.9 10.9 10.0 #4 20.9 Min. 20.0 Min. 100.0 100.0 Fine Fraction #4 0.0 100.0 0.0 100.0 #8 32.6 67.4 35.6 54.4 #16 18.9 48.5 19.2 35.2 #30 15.9 32.6 16.9 28.3 #50 15.0 17.6 13.7 14.6 #100 8.1 '9.5 6.4 8.2 #200 4.3 5.2 3.6 4.6 Pan 5.2 4.6 100.0 100.0 10 Table 2-3. Specific Gravities and Absorptions of Aggregates. (Source: Buck)(4) Bulk Specific Gravity Saturated Percent Aggregate . Surface - Dry Absorption Crushed Siliceous Concrete Coarse 2.43 4.0 2.44 4.3 Fine 2.34 7.6 ---- 9.0 Crushed Calcareous Concrete (Coarse 2.52 3.9 Chert Gravel 2.52 2.6 Limestone 2.67 0.8 Natural Sand 2.63 0.4 Table 2-4. Specific Gravities of Recycled Concrete From the Iowa Project. (Source: Bergren and Britson)(3) Material Specific Gravity Crushed PCC 2.457 Crushed PCC and Asphalt Concrete Combined 2.445 11 and natural sand. Specific gravities for both the plain PCC and the combination of materials are in close agreement with those reported by Buck (4) for materials with the same basic composition. 2.1.3 Durability Factor The durability factor is an indicator of the resis- tance of concrete to rapid freezing and thawing and is a test used to compare aggregates on the basis of standard mix design. On a range from 0 to 100, a higher numerical value would indicate greater resistance. Buck's (4) test results were extremely low (Table 2-5). However, when com- pared to control aggregates, the resistance to freezing and thawing was significantly improved for the aggregate pro- duced by crushing chert concrete and essentially comparable when aggregate was made from limestone concrete. Mix de- signs for all tests were approximately equal (Table 2-6). Laboratory data (Table 2-7) from.the Iowa (3) tests indicated higher values with the factor given for the mix containing asphalt concrete as part of the aggregate con- sidered of doubtful durability. This comparison may not be valid since different designs were used for each mix. Such related information as values for the water-cement ratios and air contents of the laboratory mixes were not reported. 12 Table 2-5. Durability Factor for Concrete Beams in Accelerated Freezing and Thawing. (Based on Buck)(4) Durability Factor Mixture l 2 3 Combined 1 4 4 2 3 2 28 22 19 23 3 30 28 25 28 4 62 -- -- -- 5 45 -- -- -- Table 2-6. Selected Physical Properties of the Five Concrete Mixtures Tested. (Based on Buck)(4) Cement Slump Air Content Aggregate Mix Round (in.) (Z) (lb/yd) Coarse Fine 1 1 2-1/4 6.0 461 2 2-1/2 6.3 461 Chert Gravel Sand 3 2-1/2 6.3 461 2 1 2-1/2 5.7 461 2 2-1/2 5.8 461 Chert PCC Sand 3 2-1/2 6.0 461 3 l 2 6.3 498 2 2 6.0 508 Chert PCC Chert PCC 3‘ 2 5.9 508 4 - 2—3/4 6.0 508 Limestone Sand 5 - 2-1/2 6.1 489 Limestone PCC Sand 13 mm owe .<.m «m u .<.o cc omu< .Ho one m «a mqoa .<.m on u .<.o on om .uo «on N mm mmo .<.m oq u .<.o ow om .uo «on H Houomm oooo< coauwoooum ooze A.nHv xwz huwawnmuno ocmm oumwouww< oumwouww< uaoEoo unmouom AMVAaOmunem was Couwuom ”mousomv .mHouomm zuwafinmuaa m30H .msm oHan 14 2.2 Physical Properties of Concrete Made with Recycled PCC Aggrggate There are a number of parameters involving the appli- cation of the properties of Portland cement concrete to engineering design with those related to strength considered most important. 2.2.1 Flexural Strength The flexural or bending strength of concrete is used for the determination of pavement design in all contempor- ary methods. An average 28-day test value of 650 psi is often considered as a standard design strength for pave- ments (46). Of the four mixes used on the Iowa (3) project (Table 2-8), mixes A and B containing crushed PCC indicated higher than normal flexural strengths (Table 2-9). This agreed with previous conclusions by Gluzhge (13) that flex- ural strengths will be higher compared to compressive strengths. The mixes C and C-3 containing crushed asphalt concrete were significantly lower. 2.2.2 Compressive Strength Compressive strengths of concrete are normally used for determining design of buildings and bridge structures. In addition, compressive strengths are often used to com- pare concrete mixes made with different proportions of cement, aggregates, and other variables. 15 Table 2-8. Iowa Project Mix Proportions. (Based on Bergren and Britson)(3) Basic Quantities Absolute Volume Cubic Yard Mix "A": 35Z C.A. - 65Z F.A. Cement .106611 564 1b. Water .181030 305 lb. Air .060000 Agg. (Crushed PCC) .300429 1244 lb. F. Agg. (Sand) .351930 1589 lb. w/c = 0.54 lb./1b. Max. w/c = 0.613 1b./1b. Project Average - 0.514 Mix "B": SOZ C.A. - SOZ F.A. Cement .106611 564 lb. Water .164411 277 1b. Air .060000 Agg. (Crushed PCC) .440117 1822 lb. Agg. (Sand) .228861 1033 lb. w/c = 0.49 1b./1b. Max. w/c = 0.556 1b./1b. Project Average - 0.456 Mix "C”: Crushed A.C. & P.C. (Note: Approximately 80Z C.A. and 20Z F.A.) Cement .088842 470 1b. water .150760 254 1b. Air .060000 Aggregate .700398 885 1b. w/c = 0.54 lb./1b. Max. w/c = 0.613 1b./1b. Project Average — 0.550 Mix "C3”: 85Z A.C. & P.C. - lSZ Sand (Note: Approximately’ 65Z C.A. and 35Z F.A.) Cement .088842 470 lb. Water .150760 254 1b. Air - .060000 Crushed A.C. P.C. .595338 2452 lb. Aggregate (Sand) .105060 474 1b. w/c = 0.54 1b./lb. Max. w/c = 0.613 lb./1b. Project Average - 0.500 16 om.o 0cm muo mm.o owm u o¢.o Ham m Hm.o was < oeumm uaoEoouHoumB Awwmv someonum Hopsxoam xwz owmuo>¢ . AmVAGOmuflHm one sowwuom "oonsomv .uoomoum Houcoawuomxm «30H onu Eoum muadmom umoH suwcouum Houdxoam zmmumm .alm oHan 17 Buck (4) offered the most comprehensive study concern- ing compressive strengths of concrete made with recycled PCC. The results of his tests (Table 2-10) indicated con- crete mixes with crushed concrete aggregate produced lower compressive strengths than control mixes. Frondistou- Yannas (12), who also reported the differences between con- cretes made with crushed FCC and control aggregates at various water-cement ratios (Tables 2-11 and 2-12), drew the same conclusion. Results of average field tests for the Iowa (3) experimental project indicated more than ad- equate strengths (7) for concrete made with recycled PCC aggregate (Table 2-13). The Frondistou-Yannas (12) tests were made on concrete with an abnormally high water-cement ratio and tested at an early age. However, the results of tests for the concrete using regular cement and recycled PCC aggregate were extrap- olated and compared to the other studies with respect to mixes having approximately the same water-cement ratio (Table 2-14). It was assumed that 15-day tests were 80 percent of 28 day values. 2.2.3 Other Physical Properties of Hardened Concrete Buck (4) also performed tests to investigate two other parameters to provide information for comparing the physical properties of concrete made with recycled PCC to concrete made with conventional aggregate. These were determina- tions of the linear coefficient of expansion (Table 2-15) 18 Table 2-10. Concrete Mixtures Tested. Average Compressive Strengths of the Five (Source: Buck)(4) Compressive Strength (psi) Mixture Number Round 7 Days 28 Days 58 Days 90 Days 180 Days 1 1 2,800 4,420 5,160 5,230 5,660 2 2,360 3,840 4,400 4,890 5,120. 3 2,520 4,160 4,530 5,070 5,050 Combined 2,590 4,140 4,700 5,060 5,280 2 1 1,910 2,880 3,480 3,900 3,850 2 1,990 3,210 3,620 3,840 4,090 3 2,030 3,050 3,650 3,900 4,140 Combined 1,980 3,050 3,580 3,880 4,030 3 1 2,440 3,210 3,780 4,270 4,570 2 2,210 3,570 3,930 4,440 4,640 3 2,240 3,430 3,700 4,120 4,340 Combined 2,300 3,400 3,810 4,280 4,520 4 --- 3,180 4,510 4,790 5,320 5,530 5 --- 2,580 4,150 4,000 4,660 4,840 19 Table 2-11. Relationship Between water-Cement Ratio and Compressive Strength. Cement: Portland Cement Type III; Fine Aggregate: Ottawa Sand. Tested at 8 Days. (Based on Frondistou-Yannas)(12) Compressive Strength (psi) water-Cement Ratio Recycled PCC Granite Gravel Concrete Concrete 3400 3700 0.55 2100 2150 0.65 1300 1600 0.75 Table 2-12. Relationship Between Water-Cement Ratio and Compressive Strength. Cement: Portland Cement Type I; Fine Aggregate: Granite Sand. Tested at 15 Days. (Based on Frondistou-Yannas)(12) Compressive Strength (psi) water-Cement Ratio Recycled PCC Granite Gravel Concrete Concrete 2600 3500 0.55 2200 2500 0.65 1700 1500 0.75 20 Table 2-13. 28-Day Compressive Strength Test Results from the Iowa Experimental Project. (Source: Bergren and Britson)(3) Average Mix Compressive Strength (psi) water-Cement Ratio A 4413 0.51 B 4292 0.46 C 2250 0.55 C-3 2290 0.50 Table 2-14. Compared Compressive Strengths from Three Studies water-Cement Compressive Information Source Ratio Strength (psi) Bergren and Britson (3) 0.51 4413 Buck (4) 0.49 3050 0.49 3400 0.49 4150 Frondistou-Yannas (12) 0.50* 3500* *Extrapolated values 21 Table 2-15. Linear Coefficient of Thermal Expansion of the Five Concrete Mixtures Tested. (Based on Buck)(4) Linear Coefficient of Expansion Mixture Number 1 2 Combined 1 6.3 --- --- 2 6.1 --- _-_ 3 5.6 5.7 5.6 4 3.6 . --- _-- 5 4.7 --- --- 22 and the length change of concrete specimens stored at con- stant moisture and temperature (Table 2-16). The results correlated exceptionally well and were well within the acceptable range of 2.5 to 8.0 and maximum of 0.025 percent respectively (40,42). Because of the apparently tight con- trols used in these experiments, it can be assumed that concrete made with recycled PCC aggregate will react normally with respect to these properties. Tests by Frondistou-Yannas (12) to determine the re- lationship of modulus of elasticity to various water-cement ratios (Figures 2-1 and 2-2) were made with concrete not representative of mixes normally used for construction (7). Therefore, the results were not considered conclusive. 2.3 Economics of Crushing PCC for New Pavements Intuition demands that, if an existing PCC pavement surface must be removed because of structural deficiencies, it would have to be more economical to re-use the resulting waste material as aggregate rather than haul the material to a dump site and haul in new aggregate for replacement construction. This, of course, would be dependent upon the expense of crushing operations, haul distances, and the quality of the recycled aggregate; 2.3.1 Previous Economic Evaluations There were no reported studies dealing specifically with the economics of recycling old PCC pavements for new, 23 Table 2-16. Length Changes of Concrete Specimens Stored at Constant Moisture and Temperature. (Based on Buck)(4) Length Increase (percent) Mix Round Specimen 28 Days 90 Days 1 1 1 0.013 0.019 2 5 0.016 0.018 3 9 0.010 0.008 Average 0.013 0.015 2 l 1 0.014 0.023 2 5 0.010 0.011 3 9 0.012 0.014 Average 0.012 0.016 3 l 1 0.017 0.036 2 5 0.007 0.009 3 9 0.007 0.011 Average 0.010 0.019 4 1 1 0.003 0.001 2 5 ---------- 3 9 ---------- Average 0.003 0.001 5 l 1 0.003 0.002 2 5 ---------- 3 9 ---------- Average 0.003 0.002 24 5‘ 3.0- «4 -3 Conventional 3 Concrete «W4 2.0.. \ a s. \ 1H,. Recycled / \ 3.3 éfiifiiiiie \ sx1.0— \--——__, H 5m vo o z: 0 l I l I I 0.50 0.55 0.60 0.65 0.70 0.75 0.80 Water/Cement Ratio - By Weight Figure 2-1. Relationship Between Water-Cement Ratio and Cement: Portland Cement Modulus of Elasticity. Type III; Fine Aggregate: Ottawa Sand. (Based on Frondistou-Yannas)(12) 3.0,_ 5‘ Conventional ‘3 Concrete «4 #3 '31; 2.0- .“\ e19. -\ \~ Q-ho \ OS Recycled / y 3” 1.0L Aggregate ‘ ~ ‘. Fa Concrete and 'o >3 0 l. 1 l 1 1 0.50 0.55 0.60 0.65 0.70 0.75 0.80 Water/Cement Ratio - By Weight Figure 2-2. Relationship Between Water-Cement Ratio and Cement: Portland Cement Modulus of Elasticity. Type I; Fine Aggregate: Frondistou-Yannas)(12) Granite Sand. (Based on 25 although some background information was available. Two researchers at the Massachusetts Institute of Technology (11) made a comprehensive study of average equipment and production costs related to crushing PCC demolition debris. Theorizing this debris would be contaminated with other materials, they designed a crushing operation with facil- ities for removing any undesirable products (Figure 2-3). Based on these factors, they estimated the plant price of recycled PCC aggregate to be 67 percent of the plant price of conventional aggregate. Since previous research resulted in a determination of reduced strength and stiffness in concrete made with recycled concrete, the researchers predicted that concrete members produced with recycled PCC aggregate would require 20 percent more volume than members produced with convention- al aggregate. This canceled the cost advantage unless the source of conventional aggregates were at least 15 miles farther than the source of recycled aggregates. Ray and Halm (21) reported a preliminary study of energy requirements to produce one mile of pavement (10 inches thick and 24 feet wide, or 3911 cubic yards) com- paring the use of conventional aggregate, crushing the existing pavement, and hauling aggregate from a commercial recycling plant for the concrete mix (Table 2-17). It was evident that the energy requirements for breaking the old pavement were included in the calculations and should be 26 DEMOLITION DEORIS 1 NONCONCRETE OEan r Is 1 ’1 PRECLEMUNC PROCESS : L _.l 1 Iosrtv CONCRETE DEM: VIamrmG FEEDER RE-BAR ”rm" kaL causuEn I ”can“: coflvcvon SEPARAYOR eELr COARSE MOSTLY WOOD MATERIAL wasaEa- CONVEYOR DEWAIEREI BELT (T—‘TS I; .11 count: \\‘\. ovenson AGGREGATE 1, occho ‘/ SCREEN CONVEYOR BELT FINISHED PRODUCT: RECYCLED EGGREGATE or REQUIRED GRAOAIION Figure 2-3. Schematic Flow Chart of Recycling Plant. (Source: Frondistou-Yannas and Itoh)(1l) 27 deleted if this operation.must be accomplished in the regular progress of a project. However, their conclusion was that, when the hauling distances for conventional aggre- gates exceeds 50 miles, recycled pavement becomes a de- sirable alternative. Table 2-17. Energy Requirements for Recycled PCC Aggregate Compared to Conventional Aggregate. (Based on Ray and Halm)(21) Aggregate Haul Distance Energy Used (Miles) (BTU X 1061* Natural Aggregates 10 7931 20 7977 50 8115 100 8346 Recycled Pavement On the Job Plant 8148 Recycled Concrete 10 7829 *Calculated on the basis of aggregate required for one mile of pavement. Loken (18) reported an estimated savings of one-hundred thousand dollars by the Iowa Department of Transportation on an unreported 17 mile pavement project using recycled PCC for aggregate. Personal communication with this agency 28 revealed the particulars of the project were not available at this time. 2.4 Concrete Mix Design The basic components of a Portland cement concrete mix- ture are cement, fine aggregate, course aggregate and water. Determinations of the relative proportions of these compon- ents range from.the, now largely outmoded, 1:2:3 volumetric ‘method requiring one part cement, two parts sand, and three parts coarse aggregate with sufficient water added to pro- vide a workable mix (42) to theoretical methods based on laboratory analysis. Most contemporary methods of mix de- sign have been derived from.work done by Abrams in 1918 (2, 7,38) and Talbot and Richart in 1922 (2,36,38). Abram's major contribution was the concept of the relationship of water-cement ratio to strength. Talbot and Richart investi- gated the application of the voids-cement ratio to mix design which contributed the concept of the absolute volumes of component materials. 2.4.1 Portland Cement Association Method The Portland Cement Association method utilizes Abrams' water-cement ratio theory, compressive strength requirements, and observed mixture qualities in a series of trial mixes to determine the relative proportions of materials (7). The following general steps are used in the mix design process: 29 Step 1. A compressive strength requirement is deter- mined by specification or other criteria. Step 2. Select the required water-cement ratio (W/C) from Figure 2-4 where: Ww = 2’1 W/C Wc ( ) where: w = Weight of water; We Weight of cement. Step 3. From.the weight of the cement selected for a trial batch, determine the weight of the water required from: ww = Wc-W/C _ (2-2) Step 4. Saturated, surface dry, fine and coarse aggre- gates are weighed and mixed with the cement and water in proportions required to bring the mixture to desired con- sistency and workability. Step 5. Aggregate not used in the trial mix is weighed and subtracted from original weights, the unit weight of the mixture is determined, and the weights of component materials per unit volume are determined through appro- priate calculations. A series of trial mixes are made by varying the amount of fine aggregate and holding the other materials constant. 30 The results are plotted and the most economical mix, with respect to ratios of cement and sand (Figure 2-5), is selected holding the water-cement ratio constant. 6000 Normal Concrete 5000 .. / 0:4 U) D. n: S 4000 I— z: :3 [-i (I) g A-E Concrete :3 3000 - U) E C) G: 2000 - l 1 I l 0.3 0.4 0.5 0.6 0.7 0.8 WATER-CEMENT RATIO Figure 2-4. Typical Trial Mix Strength Curves. (Based on Portland Cement Association) (7) 31 Cement content + l‘\\ I Optimum fine I agg. content Fine aggregate, per cent of total aggregate + Figure 2-5. Typical relationship between percentage of fine aggregate and cement content for a given water- cement ratio and slump. (Based on Portland Cement Association)(7) 32 2.4.2 American Concrete Institute Methods Two methods of mix design are offered by the American Concrete Institute (24). Each incorporates a comprehensive set of empirical criteria to aid in selecting design pro- portions (Tables 2-18 through 2-23). Weight Method The weight method is basically the same as that pre- viously described for the Portland Cement Association method except that determinations of the unit weight of the coarse aggregate and the gradations of both the fine and coarse aggregates are required to determine factors or proportions from.the tables. Steps utilized in formulating a mix design for one cubic yard of concrete are: Step 1. Select the appropriate weight of water from Table 2—19. Step 2. Calculate the weight of cement from.the water- cement ratio related to the required compressive strength in Table 2-20. The water-cement ratio is subject to con- straints in Table 2-21. Step 3. Multiply the selected workability factor in Table 2-22 times the unit weight of coarse aggregate times 27. Step 4. Subtract the total weight of the materials in Steps 1 through 3 from the estimated weight of fresh concrete in Table 2-23 to determine the weight of the fine aggregate. The trial batch is then tested for desired qualities and adjustments are made as necessary. 33 Table 2-18. Recommended Slumps for Various Types of Construction. (Source: American Concrete Institute)(24) Types of Construction Slumpyyin. Maximum Minimum Reinforced foundation walls and footings 3 1 Plain footings, caissons, and substructure walls Beams and reinforced walls Building columns Pavements and slabs moored: l—‘I—‘l—‘HH Mass Concrete 34 o.e m.¢ o.m m.m 0.0 0.0 0.5 m.n madmomxo oEoHuxm o.m m.m o.e m.e m.¢ o.m m.m 0.0 oupmoaxo oumuoooz o.H m.H o.~ n.~ o.m m.m o.a m.a muamoaxm eHHz announce HHo poached oopaoafiooom III omm 0mm 0mm OHM mmm mam mom 5 co 0 omm 0mm mom mmm mmm mom mmm can a on m oom mam can emu ohm owm mmN mom N on H ououocoo oochuucoIhH< N.o m.o m.o H m.H N m.~ m ens emaameuem mo unpoem oumEonumm< III mam oom mHm oem com mwm CHe 5 cu m omm mom mwm com mum can mom mwm a co m OHN oem com mum com mHm mmm 0mm N on H ououocoo oocHouuGquHmIcoz .cH .2H m .cH m .cH ~\HIH .:H H .cH ¢\m .GH «\H .cH w\m AGNVAouDuHumGH ououoaoo GmoHHoE< ouwmouwmm mo moNHm EDEHRME HmcHEoc ooumoHoGH How ououocoo mo oz do pom pH .Houmz .sa .QSDHm ”ounpomv .moumwohww¢ mo moNHm EpBmez HmaHEoz paw mmEsHm unoHoMMHQ How mufioEoHHdoom oceanoo HH< one noun: waHtz oumEonumm< .mHIN oHan 35 Table 2-20. Relationships Between Water-Cement Ratio and Compressive Strength of Concrete. (Source: American Concrete Institute)(24) Water-cement ratio, by weight Compressive strength at 28 days (psi) Non-air-entrained Air-entrained concrete concrete 6000 0.41 --- 5000 0.48 0.40 4000 0.57 0.48 3000 0.68 0.59 2000 0.82 0.74 36 m¢.o oe.o moumMHpm Ho Mont mom on pomomxo ohsuosuum 00.0 .mmHHHUUDHUm HNSUO HH< Hooum Ho>o Ho>oo .GH H cusp mmoH suHB mGOHuoom me.o can Axuo3 HmucmEmauo .mowpoH .mHHHm .mnudo .mwcHHHouv wcoHuoom GHSB wGHBmsu mam waHNoon ou oomoaxo paw hHuaopoon no ounposuum mo cozy szpopaHucoo upB oupuosuum .moudmoaxm ouo>om CH AqvaousuHumcH ououoaoo cmoHHoE¢ ”moupomv ououocoo pom mOHpom ucofiooIHoumE oHnHmmHEhom afifimez .HNIN oHHMH 37 Table 2-22. Volume of Coarse Aggregate Per Unit of Volume (Source: American Concrete Institute)(24) of Concrete. Maximum size of aggregate, Volume of dry-rodded coarse aggregate per unit volume of concrete for different fineness moduli of sand in. 2.40 2.60 2.80 3.00 3/8 0.50 0.48 0.46 0.44 1/2 0.59 0.57 0.55 0.53 3/4 0.66 0.64 0.62 0.60 l 0.71 0.69 0.67 0.65 1-1/2 0.75 0.73 0.71 0.69 2 0.78 0.76 0.74 0.72 3 0.82 0.80 0.78 0.76 6 0.87 0.85 0.83 0.81 38 Table 2-23. (Source: First Estimate of Weight of Fresh Concrete. American Concrete Institute)(24) First estimate of concrete weight, Maximum size of aggregate, in. lb per cu yd Non-air-entrained Air-entrained concrete concrete 3/8 3840 3690 1/2 3890 3760 3/4 3960 3840 1 4010 3900 1-1/2 4070 3960 2 4120 4000 3 4160 4040 6 4230 4120 Absolute Volume Method Although a detailed laboratory analysis of the physical prOperties of component materials is required before apply- ing the absolute volume method, it is the most exact means of designing concrete mixtures of those commonly used. In this case, the total volume displaced by water, air, cement, and coarse aggregate, as determined from the tables or specifications, is subtracted from the unit volume of con- crete to obtain the required volume of fine aggregate. For the purposes of this research, this procedure was converted to formula form using the following notations: Wd, Wb, We, WD = Weights of fine aggregate, coarse aggregate, cement, and mixing water respectively. Ga, Gb, Gc= Specific gravities of fine aggregates, coarse aggregate, and cement respectively. V = Unit volume of fresh concrete. V Vb, Vc, Vw, VA = The absolute volume of fine aggre- a, gate solids, coarse aggregate solids, cement solids, mixing water, and entrained or entrapped air in the unit volume. Yw = Weight per unit volume of water. 1 Percent of entrained or entrapped air. After determining known quantities from the tables: vb = ___Wb <2-3) Gwa V0: i— (2_4) Gch 40 vA = xv (2-6) Va = V - Vb - V0 - Vw - V1 (2-7) Wa = Va‘Ga'Yw (2—8) In addition to this basic design, allowances are made for the absorption of the fine and coarse aggregates to cal- culate the total quantity of water required for the mix. 2.4.3 Michigan Department of Transportation (Mortar Voids) Method. The theory proposed by Talbot and Richart (36) that there is a definite relationship between concrete strength and the ratio of the volume of cement to the volume of voids in the mortar (water and air) formed the basis for Michigan mix design. This relationship is true provided there is enough mortar to fill the spaces between the coarse par- ticles of aggregate (31). In the mortar voids method, tests are performed to determine the amount of water required to provide the most dense mortar with a selected ratio of dry mortar materials which, therefore, establishes a basic water content (Figure 2-6). A factor termed relative water content (RIW.C.) derived by empirical methods for various uses, is then applied to determine the actual amount of mixing water required. Relationships between the various parameters are illustrated in Figure 2-7. Coarse aggregate require- ments are determined by applying a workability factor (b/bo), 41 Mortar / VOLUME / / / l MiXing / I Water / 3 u | u \N / m a / :3 I 3 ’ S I 8 / m :5 / m | / “1| WATER CONTENT Figure 2-6. Typical Curve Showing the Relationship Between the Water Content of Mortars and the Volume of Mortar. (Source: Bauer)(2) 42 Auvnumpmm "woupomv .OHumm oommqucofioo one nuwcouum o>HmmoHoEou cooSDom eHsmGOHumHom HmoHo%H .NIN ohame OHH¢M mo—‘ ‘L'5°'"°'7N‘ I— 3 0 l 5 2 2 15 5 5 2' 9 6 .—I P___ G I 15 0 5 13 7 5 2 9 5 _ Coono A.',.,".: L. 32 143 8 15 9 4 29 3' 33 147 l 161 I. 2'; 4 I- *-—' 31. {1,35 1 (’3 3 29 3 —- Soundnau Lott. ootcont L— 35 1433 1652 :92 ._ Laboratory No. I_ 36 1 42 2 I6 7 2 291 .__, Abrasion, ”ICC!" of root 32 37 I nos I 1.5.91 I :91 L_ L“mm”... A 791-492 REMARKS: -.Thio tho" Tot uao with aononta. at tho data shown abavo, from tho IaIIo-Ing IOUIGOI: Aotna Pootlooo Gonovol-Pauldina, OhIo Dundao Ponn-Dilio Mod“. - All Plants Huron 'yondotto .Tyaucal unIt woight (dry Ioooo) a. caarao 0"70'... aa doocnbod abava it 82 15”“; It. 45 2.5 Rigid Pavement Design The predominate method used in the design of rigid highway pavements in the United States is based on empirical determinations of the effect of the magnitude and repeti- tions of loads and environmental factors peculiar to the various geographical locations (46). Therefore, most states use a standard cross section for the surface structure with provisions for correcting deficiencies in the subgrade. Inasmuch as this research is primarily interested in thickness requirements for the pavement surface structure using recycled PCC for aggregate in the concrete mixture, factors leading to the development of contempory pavement design were investigated. 2.5.1 Theoretical Stress Ana1ysis In 1926, Westergaard (43) published the results of an analytical study defining stresses in concrete pavements due to loading. His assumptions were that: 1. The pavement slab acts as a homogeneous, elastic solid in equilibrium. 2. The reactions of the subgrade are vertical and proportional to the deflections in the slab. Although three cases for determining maximum stress were presented, the stress formula for corner loading of the slab (Figure 2-8) was considered most critical. 46 / /’ k \ \ _) a q— Figure 2-8. Westergaard's Case for Corner Loading. (Source: Westergaard)(43) 47 Westergaard (43) defined two identities necessary in deriving his formula as the modulus of subgrade reaction (k) and the radius of relative stiffness (Z) where: k = .3. (2-9) 2 where: P = Reaction of the subgrade per unit area; z = Deflection of a point. and: z = \I/ Eha (2-10) 12(1-u2)k where: I E = Modulus of elasticity of the concrete; h = Thickness of the slab; u = Poisson's ratio for concrete. The equation for maximum tensile stress (cc) at a corner is: 3 _0.15 o = 3P 1 - Eh a 0,. (2-11) 0 h2 12(l-u2)k ‘ where : P = Point load; a1 = Defined in Figure 2-8. Simplified: P 0.6 06 = :2 L1 -(J%L) (2-12) 48 2.5.2 Portland Cement Association Method This method modifies Westergaard's static stress analy- sis to allow for repeated load applications (46) and offers a simplified means of determining stress in the pavement under various axle loads (Figure 2-9 and 2-10). The ratio of this stress to the modulus of rupture (flexural strength) of the concrete is compared to the allowed repetitions in Table 2-25. The projected number of repetitions for each class of axle loadings over the design life of the pave- ment are then weighted as a percentage of the allowable repetitions. General theories pertinent to this method are that: 1. If the stress ratio is less than 0.51, the con- crete will sustain an unlimited number of stress repetitions without failure. 2. The design is corrected if the sum of percentages used by repeated loadings over the design life is under 100 percent. 2.5.3 AASHO Interim Guide Method The results of AASHO Road Tests studied from 1958 to 1960 provided the basis for this method of pavement design and is the method used by most states for actual design or to verify standards (37). Basic design procedure incor- porates the use of nomographs (Figure 2-11 and 2-12) which represent the equation developed from strain measurements and condition determinations during the study period (1). 49 550 500 2 Stress (psi) 50 12141618 22242628 32343638 42444648 10 20 3O 40 50 Single-axle load (hips) Figure 2-9. Design Chart for Single-Axle Truck Loads. (Source: Portland Cement Association)(7) Ov\ 550 Stress (psI) 300 250 ’ ' . 20 40 60 80 100 5380*? ‘3 \ \\ \ \ \\\\ \{\\\\\\\¥ 4§£N7*g.0\\“‘\ \QY§§§S$§L ”310A \\‘\\\\\\\x\\ I. 150T\\\‘\ \\\\ l\\\\\\\\\ V\\ ‘ \:‘\\:1\ \ \\\\\\\\\\\\ ‘°°,5 \ \\\\ \\\\\\\\ §h>.>.}\\.\>>>\\\\.\>>>%\ Tandem- axle load (:25) Figure 2-10. Design Chart for Tandem-Axle Truck Loads. (Source: Portland Cement Association)(7) 51 Table 2-25. Stress Ratios and Allowable Load Repetitions. (Source: Portland Cement Association)(7) Stress Allowable Stress Allowable Ratio Repetition Ratio Repetition 0.51 400,000 0.69 2,500 0.52 300,000 0.70 2,000 0.53 240,000 0.71 1,500 0.54 180,000 0.72 1,100 0.55 130,000 0.73 850 0.56 100,000 0.74 650 0.57 75,000 0.75 490 0.58 57,000 0.76 360 0.59 42,000 0.77 270 0.60 32,000 0.78 210 0.61 24,000 0.79 160 0.62 18,000 0.80 120 0.63 14,000 0.81 90 0.64 11,000 0.82 70 0.65 8,000 0.83 50 0.66 6,000 0.84 40 0.67 4,500 0.85 30 0.68 3,500 ---- ~- 52 s 3" § . § § § I I I I . I .. l I I .NOIIDVBU BOVUDGOS JO smnoow-H / / / / / / / o 9" 0 ° F _ “O‘HL 9‘1; sauoNl 493" \ \ \ \ \ \ \ \ § § 8888 L IlIlIlIlil 31383403 NI 55381.5 DNIMUOM- '9 \ \ \ \ mound snsnvuv' uvax oz) snouvanadv mm 31“ 319m: dm- eI\ nwo 1N31VAInoa g gogg \§_§§§_§§_c8>_ 9 3 9.". \snmlnvai I L 1411111 1 lLJlllllluJ\ 11111111 I T T IITIEII I I ‘1’". 1' l O O O 3 3.. § 2 8 § 8 §. - N In :3 8 SONVSOOHL 'SNOILVDHddV OVO‘I JWXV SWONIS dIM-Ol .LNJWVAIHDJ 'IVLOL AASHO Interim GuideXl) (Source d Pavements, Pt = 2.5. 1gi Design Chart for R Figure 2-11. LINE PIVOT 53 § § § § 1 l 1 l 1 l I l NOInvau aovuoens JO smnoow-u I L—so / . . n : 9]., o S3H3NI ' ‘93"‘3‘H‘L gVWS‘ O \ § § §\§ §§ J 4 l I I ILLL anuauoa NI scams DNINUOM- '5 (OOIU3d SISA‘IVNV UVBA OZ) 5NO|1V3HddV OVO‘I 31XV 319Nl5 «flit-9| A'IIVO LN3'IVMOO3 2 a a §§§§\§.§§-§§§§ §§ §§§ ggg d sonvsnom. 'suouvonaav ovm 31am 31am: aux-on ma‘wmnoa “IVLOL Design Chart for Rigid Pavements Ptl= 2.0. AASHO Interim Guide)(1) (Source: Figure 2-12. 54 Use of the nomographs requires an evaluation of the follow- ing parameters: 1. Expected terminal serviceability index (Pt)° 2. Equivalent 18-kip single-axle loads over the design life of the pavement. 3. Modulus of subgrade reaction (k) as previously defined. 4. The working stress (ft) in the concrete. An empirical ft value of 0.75 times the modulus of rupture of the concrete was established from road test results. CHAPTER III RESEARCH MATERIALS AND MIX DESIGN The materials obtained for research were strictly re- lated to recycling an existing PCC highway pavement for the purpose of using the material in the mix for the new pave- ment surface. Mix design procedure followed, as closely as possible, Michigan Department of Transportation methods (31). 3.1 Component Materials In order to provide a valid correlation in research data, it was considered necessary to collect a sufficient quantity of materials required to complete all phases of the research process. Background information relative to the materials used was also considered necessary. 3.1.1 Materials for Recycling One of the main purposes of this research was to pro- vide a basis for determining, as closely as possible, the characteristics of recycled aggregates under field condi- tions. In addition, another purpose was to devise a method of predetermining material properties for design purposes. PCC Material The Michigan Department of Transportation has been involved in a major pavement joint repair program in recent 55 56 years. In this process, pavement sections surrounding transverse joints experiencing mechanical failure (Figure 3-1) are removed (Figure 3-2) and replaced with a quick- set concrete patch. Waste materials are normally hauled to a fill site. A project of this type was completed in 1979 on a section of I-96 between Novi and New Hudson in Michigan. The waste concrete was disposed of in a nearby abandoned gravel pit area where a pond was being filled (Figure 3-3). Three slab sections of this material were selected for research. In order to simulate procedures normal to those re- quired to completely remove an existing pavement, the sections were broken into maximum three-foot square pieces (Figure 3-4). It was observed that most of the temperature ‘reinforcement present in the slabs broke along the lines of fracture in the concrete. The material was then loaded and hauled to a crushing operation in Detroit. Prior to the breaking operation, two representative six-inch cores were drilled from each slab (Figure 3-5). Material from this source was designated as A for the broken material and A-1 for the cores. Six cores were also taken from a section of I-94 Business Loop near Battle Creek, Michigan to provide cor- relation. These were designated material B. In addition, twelve cores were obtained from a section of I-94 near Jackson, Michigan. This pavement had a nominal three-inch 57 Figure 3—1. Typical Transverse Joint Failure Figure 3-2. Removal of Slab Sections for Joint Repair. 58 Figure 3-3. Disposal Site for Waste Pavement Sections. Figure 3-4. Breaking Pavement Slabs for Research Material. 59 Figure 3-5. Coring Pavement Slabs. bituminous concrete overlay. Since it was intended to utilize bituminous concrete material as part of this re- search, six of the cores with the overlay removed were designated aggregate material C and those with the over- lay as C-l. The original Portland cement concrete mixes for all of the indicated sources were made with natural gravel and sand conforming to the grading requirements listed in Tables 3-1 and 3-2. The two grades of coarse aggregate were proportioned on the basis of 50 percent each by weight. Basic mix design was for 5-1/2 sacks of cement per cubic yard with air entrainment (31,52,33). Background histories for each source are given in Table 3—3. Table 3-1. 60 Gradation Requirements for Coarse Aggregates Used in Source Material for Recycling. (Source: 1942 and 1950 Standard Specifications for Road and Bridge Construction, Michigan State Highway Department) Michi an Grade 4A Michi an Grade 10A Sieve m Passing . Passing_ 2-1/4" 100 2" 95-100 1-1/2" 65-90 100 1" 10-40 95-100 1/2" 35-65 3/8" 0-5 #4 0-8 Table 3-2. Gradation Requirements for Fine Aggregate Used in Source Material for Recycling. (Source: 1942 and 1950 Standard Specifications for Road and Bridge Con- struction, Michigan State Highway Department) Michigan Grade 2N8 Sieve % Passing 3/8" 100 #4 95-100 #8 65-95 #16 35-75 #30 20-55 #50 10-30 #100 0-10 L.B.W. 3 maximum 61 NNGH I “ANHHQPO @UUHUCOU W50CH§UHm COWXUQH. mama I ucoam>mm oum :m qmnH Huo mam o mmma I amaum>o ououocoo msocwESuwm mama - unm5m>mm oom :m moon mmmcamsm em-H m acmpsm 3oz nmma I uam8m>mm com :m omIH HI< cam < mouma cowuonuumcou mousom ovoo Hmwuoumz .mwoq boom cofiumunoamcmuw mo unoEuHmamo cmwwnowz Bonn mamwuoumz condom mo mmwuoumwm .mum manme '62 Field Crushing Facilities at Michigan Crushed Concrete, Inc. were used to crush the broken concrete material from the I-96 location. Normal operations at this company are to crush concrete debris and sell the resulting material for various uses. Operational steps are: Step 1. Material is dumped into an apron feeder (Figure 3-6) leading to a Hewitt-Robins 22 X 48 primary jaw crusher which reduces the material to a 5-inch maxi- mum size. Step 2. Unwanted material such as wood and steel (Figure 3-7) is hand picked. Pieces of steel getting by this point are removed by a magnet (Figure 3-8) from.the top of the belt taking the crushed product to a double deck screen. Step 3. Material in excess of 2-1/2 inches is scalped and fed into a Hewitt-Robins 12 X 48 secondary jaw crusher. All material passing the 2-1/2 inch screen is separated into the minus l-l/2 inch and 1-1/2 to 2-1/2 inch sizes on a set of the double deck screens. Material from the second~ ary crusher is returned to the screening process. Step 4. The two sizes are independently stockpiled by radial stackers. Inasmuch as the debris normally crushed at this facil- ity contains topsoil and other objectionable materials, equipment was thoroughly cleaned before crushing the re- search material. Economics did not provide for changing 63 Figure 3—6. Charging Apron Feeder at Michigan Crushed Concrete, Inc. Figure 3-7. Hand-Picking Steel and Other Material from Crusher Belt at Michigan Crushed Concrete, Inc. 64 Figure 3—8. Removal of Steel from Crusher Belt by Magnet at Michigan Crushed Concrete, Inc. the screening process to provide a more suitable grading. All crushed material was caught at the point of discharge from the radial stackers and placed in a hauling unit for transport to the writer's residence. Here, sufficient material was bagged for transport to the laboratory. Approximately four cubic yards of material for research resulted from this procedure. 3.1.2 Bituminous Material Bituminous concrete overlay materials which had been rota-milled from a project on U.S. 12 near Inkster, Michigan, and stockpiled at an asphalt plant, provided the materials required for this project. The overlays were placed in 65 successive layers in 1953 and 1972 and were, therefore, considered appropriate. This material was designated as Code E. 3.1.3 Fine Aggregate Michigan 2NS natural sand was used extensively for this research project. Forty bags (approximately 3000 pounds) were gathered at the Morgan Sand and Gravel Company near Brighton, Michigan to insure a sufficient quantity for uniformity of test results. This type of sand results from the disintegration of rocks as part of the erosion and weathering process and is the material used for, virtually, all concrete construction purposes in the State. The mate- rial was considered similar to those used in the mixes for the original concrete used for recycling. 3.1.4 Control Coarse Aggregate Since it was desirable to use a coarse aggregate simi- lar to those used in the mixes for concrete to be recycled, natural gravel meeting the requirements of Michigan speci- fications 6A was selected for the control mix. These gravels are, largely, metamorphic in nature, and contain a variety of base materials. The aggregate gradings used in the original mix were no longer available. The source of coarse aggregate used for this research was the L.W. Hall Pit near St. Johns, Michigan. Sufficient quantities were obtainable at the Michigan Department of Transportation lab- oratory to make the necessary batches. 66 3.1.5 Cement Cement used for this project was Peerless Portland Cement Type I-A meeting the requirements of Michigan speci- fications which state this material must meet ASTM Standards C150 and C359. Type I-A cement is designed to provide air- entrainment for concrete, but normally requires the addi- tion of an air-entrainment agent to provide satisfactory levels. Arrangements were made with the Peerless Cement Company in Detroit, Michigan to provide twenty bags (1880 pounds) of cement from a single manufacturing batch. Re- presentative samples were obtained from these bags and tested for uniformity and specification requirements by the company. The cement was stored in plastic bags for the period of research to avoid the possibility of pre- mature hydration. 3.2 Concrete Mix Design Used for Research As previously discussed, the Michigan Department of Transportation uses a variation of the mortar—void method for the design concrete mixtures which is closely related to the absolute volume method (31). Since this work was also related to practices in Michigan, it was decided to use the absolute volume method adjusted for empirical fac- tors relevant to current practices in Michigan. Mbst major paving projects in Michigan are accomplished with the use of Slipform pavers. Assuming a recycling 67 project would be considered major, the concrete mix was designed accordingly. 3.2.1 Mix Design Procedure Review of previous mix designs for slipform.paving in Michigan resulted in a determination that the average water-cement ratio used was approximately 0.43. In addition, the cement factor is specified as 6 sacks per cubic yard (564 1b.), the workability factor (b/bo) as 0.72, and air content as 5.5% t 1.5%. Design is based on the bone-dry weights of aggregates and on one yard of concrete (31). Using this information, put into formula form, the mix design for this research was: Wb = b/bO'V-Yb _ (3'1) Yb = Weight per cubic foot of the coarse aggre- gate in a loose, bone-dry condition. Vb = _.Eb_ (2'3) Gwa V0 = J‘L— » (2—4) Gch Wt = W/C'Wc (3-2) ‘W V, = "’ <2-5) Yw < >- ll 25 (2-6) 68 va=v -vb-vc-vw-v, (2-7) wa = Va-Ga-Yw (2-8) The total water (Wbt) required for the mix was deter- mined by the absorption of the aggregates from: Wm: = ww + AaWa + AbWb (3-3) Where : Aa = The percent absorption of the fine aggre- gate; Ab = The percent absorption of the coarse aggregate. CHAPTER IV AGGREGATE PROPERTIES Research test methods were in accordance with ASTM standard procedures (5). Certain modifications to these procedures, as applied by the Michigan Department of Trans- portation, were considered appropriate. Recycled aggregates were treated in the same manner as conventional aggregates for all experiments. Procedures are enumerated in the following standards or discussed as required: 1. Bulk Specific Gravity (Ga) and Percent Absorption (Aa) of Fine Aggregate - ASTM C 128-73 Modified. 2. Bulk Specific Gravity (Gb) and Percent Absorption (Ab) of Coarse Aggregate - ASTM C 127-77 Modified. 3. Deleterious Particles in Coarse Aggregate - Michi- gan Methods. 4. Fineness Modulus (FM) of Fine Aggregate - ASTM C 125-76. 5. Materials Finer Than Number 200 Sieve by Washing (LBW) - ASTM C 117-76. 6. Organic Impurities in Sand For Concrete - ASTM C 40-73. 7. Salt (NaCl) Content in Portland Cement Concrete - Michigan Methods. 69 70 8. Sieve or Screen Analysis of Fine and Coarse Aggregate - ASTM C 136-76. 9. Soundness of Aggregates by Use of Magnesium Sul- fate - ASTM C 88-76. 10. ‘Unit Weight of Coarse Aggregate (Yb) - ASTM C 29-78. Inasmuch as specifications relative to aggregate pro- perties vary from state to state, and because the basic research materials are peculiar to the State of Michigan, experimental results are compared to Michigan Ibpartment of Transportation specifications (35). 4.1 Material Prgparation and Gradation The preparation of recycled aggregates for use in ex- perimental concrete mixes, and for test samples, approximated field crushing operations as closely as possible. 4.1.1 iField Crushed PCC Slab Sections Three samples representing the crushed slab sections (Aggregate material Code A) were reduced to a workable size using a standard sample splitter. The reduced samples were then tested for gradation using standard sieves. Results (Table 4-1) indicate a degree of uniformity between samples. Since the larger aggregate particles were considered too large for use in normal pavement concrete, it was necessary to recrush these particles in the laboratory. A procedure was devised to simulate a field crushing operation where material exceeding a nominal one inch 71 Table 4-1. Crusher Run Gradations for Recycled I-96 Slab Sections - Cumulative Percent Passing. Sieve Sample Number 1 2 3 Average 2-1/2" 100 100 100 100 1-1/2" 97 97 96 97 l” 67 63 74 68 3/4" 51 47 60 53 1/2" 30 30 40 34 3/8" 24 22 30 26 #4 12 12 15 13 72 maximum size is scalped after primary crushing and recrushed in a secondary crusher. Individual steps in this procedure are: Step 1. Recycled aggregate is graded through a Gilson mechanical grader (Figure 4-1). Step 2. All material retained on the one inch screen is removed and recrushed in a Denver 5 X 6 inch laboratory jaw crusher (Figure 4-2). Step 3. The recrushed material is then returned to the Gilson grader and processed with the rest of the sample. For the three samples used in the initial analysis, weights retained on each screen size were used to determine gradations. Material passing the number four (#4) sieve size was separated as fine aggregate and was, therefore, not included in the calculations for the coarse fraction. Gradation test results (Tables 4-2 and 4-3) for both the coarse and fine fractions resulting from this procedure show that the material maintained the same degree of uni- formity as the original sample. Graphing cumulative percents passing on special graph paper should produce a straight line for a perfectly well- graded aggregate. For this material, the coarse and fine fractions were fairly well graded (Figure 4-3). Approximately 4000 pounds of the crushed slab material was processed in exactly the same manner. Each sieve size was bagged separately to provide material for controlled proportioning of the various sizes. The procedures 73 Figure 4-1. Gilson Mechanical Grader Figure 4-2. Denver Jaw Crusher Table 4-2. 74 Coarse Fraction Gradation Test Results for Three Samples of Recycled PCC Aggregate A - Cumulative Percent Passing. Sieve Sample Number 1 2 3 Average 1-1/2" 100 100 100 100 l" 99 96 98 98 3/4" 75 73 80 76 1/2" 41 42 -46 43 3/8" 24 24 25 25 #4 Min. Min. Min. Min. LBW --- --- --- 0.5* Passing #4** 18 20 20 19 * Average for materials from each sample. **Aggregates were split at the #4 sieve and not included in the calculations for the coarse fraction. 75 Table 4-3. Fine Fraction Gradation Test Results for Three Samples of Recycled PCC Aggregate A - Cumulative Percent Passing. Sieve Sample Number 1 2 3 Avergge 3/8" 100 100 100 100 #4 100 99 99 99 #8 63 62 60 61 #16 42 40 38 40 #30 30 28 27 28 #50 20 18 18 19 #100 12 12 12 12 LBW 6.3 6.7 6.9 6.6 PM 3.34 3.42 3.47 3.41 76 .< oumwouww< mo mcowuomuh ocfim tam omnwou mo Gowusnfluumwn wufim oHuwuumm awn.» u>u.n .27!» .z_-~\_ .2703 .275 c o. a. on 01 on 00. oo~ \ on I .hmkom 2.6 o. .333. \ .9833: E .muchaO \ 1 .I 035 0.. “Pu—mom 33.5.9.2 on \\ \\ on \ 0v \\\ \\ \\ oo oo \\\ sowuomuh wmumoo a Huomhn mfiam \ \ oo. .m-¢ «Human DNISSVd LNQDHSd 77 described in this section were established as a standard for the preparation of all recycled materials used for re- search experiments. Nine pieces of temperature steel rang- ing in length from three to nine inches were found in the entire grading process. In addition, visual observations during grading were that there were random particles of asphalt joint patching material present in the samples. 4.1.2 PCC Pavement Cores PCC pavement cores (Aggregate material codes A-l, B, and C) obtained from previously described locations were first tested for compressive strength (Table 4—4). The resulting core fragments were then crushed in the Denver jaw crusher simulating primary field crushing. After this initial crushing, exactly the same procedures as those used for the crushed slab sections were followed. Table 4-4. Average Compressive Strengths of PCC Pavement Cores from Various Locations. Aggregate Code Compressive Strength, psi A-l 5990 6500 C 5860 78 4.1.3 Laboratory PCC Test Beams In order to investigate a case where aggregates are produced from concrete originally made with recycled aggre- gates, in other words a "re-recycled" aggregate, twelve lab- oratory test beams, cast from concrete containing Aggregate A for the coarse aggregate and varying proportions of PCC and natural fines, were crushed using the established pro- cedure. This material was coded as Aggregate D. The beams had experienced 350 cycles in the freeze- thaw chamber used for durability tests and were, therefore, considered a valid approximation of concrete exposed to ex- treme temperature differentials. The crushed particles exhibited the same shape characteristics as the other re- cycled PCC aggregate, although it was difficult to identify the natural aggregates used in the original concrete. Gradations for all of the aforementioned crushed PCC aggregates are shown in Table 4-5 and 4-6. Graphs of the fine and coarse fractions indicated nearly identical crush- ing characteristics (Figure 4-4). 4.1.4 Other Research Aggregates Other aggregate materials of a recycled nature were processed in the same manner as PCC materials. Conventional sampling and test methods were used to determine the pro- perties of the natural gravel and sand used for the experi- ments . 79 Table 4-5. Gradations of Coarse Recycled PCC Aggregates - Cumulative Percent Passing. — ‘ Sieve Aggregate Code A* A-l B C D 1-1/2" 100 100 100 100 100 l" 98 98 98 97 100 3/4" 76 74 76 77 80 1/2" 74 36 36 36 40 3/8" 25 19 21 20 23 #4 Min. Min. Min. Min. Min. LBW' 0.5 0.4 0.5 0.4 0.3 Passing #4** 20 15 l6 17 21 * Average of three samples. **Aggregates were split at the #4 sieve and not included in the calculations for the coarse fraction. 80 Table 4-6. Gradations of Fine Recycled PCC Aggregates - Cumulative Percent Passing. Sieve A* A-l Aggreggte Code C D 3/8" 100 100 100 100 100 #4 99 99 99 99 100 #8 61 62 68 72 71 #16 40 38 46 48 48 #30 28 . 26 32 32 33 #50 19 17 19 20 22 #100 12 _ 10 10 12 15 LBW’ 6.6 5.6 4.1 5.8 9.1 FM 3.41 3.48 3.25 3.16 3.11 *Average of three samples. 81 com poachomm mo .Z_|‘\n .536,“ 3 .o 6. “semi: .meo.5._2 E. .mu=_c25 32m 2 «ow—«om gainer. mCOfiuomum scam paw mmumoo mo nowuanwuumfin wNHm mHowunm .27“) .2703 ”UN.” U)!” .2...) .muumwmnww< on 01 on 00. 8M .s-¢ ”Human DNI55Vd .LNBDHBd 82 PCC Pavement Cores with Bituminous Overlay PCC Pavement cores with a nominal three inches of bitu- minous concrete overlay (Aggregate material code C-l) were crushed to determine the resulting proportions of each mater- ial in the coarse and fine aggregate fractions. The bituminous concrete was approximately 25 percent of the total core volume. Only 17 percent of the total crushed material on and above the #4 sieve contained bituminous con- crete particles of which a major proportion were natural aggregate particles with thin coatings of bitumen. Crushed Bituminous Concrete The crushed bituminous concrete (Aggregate material code E) exhibited the same characteristics as the overlay material crushed with the pavement cores in that more mater- -ial passed the #4 sieve than the plain crushed PCC. In addition, much of the coarse fraction materials were natural aggregates with minimal coatings of bitumen. All materials passing the #4 sieve were thoroughly coated. Natural Aggregates A representative sample of the natural sand (Aggregate code 2N8) from the lot used for this research was tested and considered a constant. The coarse gravel (Aggregate code 6A) was tested for physical properties, only, since mix propor- tioning was based on a standard gradation. Gradations for aggregate materials discussed in this section are shown in Tables 4-7 and 4-8. Current Michigan Department of Transportation gradation limits (35) for fine 83 Table 4-7. Gradations of Various Coarse Aggregates Used for Research - Cumulative Percent Pa831ng. Sieve Aggregate Code C-l E 1-1/2" 100 100 1" 99 100 3/4" 80 90 1/2" 39 67 3/8" 23 44 #4 Min. Min. LBW --- --- Passing #4* l8 ' 31 *Aggregates were split at the #4 sieve and not included in the calculations for the coarse fraction. 84 Table 4-8. Gradations of Various Fine Aggregates Used for Research - Cumulative Percent Passing. Sieve Aggregate Code C-l E ZNS 3/8" 100 100 100 #4 100 100 99 #8 69 57 84 #16 42 32 60 #30 24 ' 19 38 #50 13 9 13 #100 7 3 3 LBW 2.5 ---- 0.6 FM 3.44 3.80 3.02 85 and coarse aggregates used in concrete mixtures for pave- ments are shown in Tables 4~9 and 4-10. 4.2 Physical Properties of Research Aggregates. In order to simplify the identification of the research aggregates, a recapitulation of aggregate material codings and sources is offered in Table 4-11. Experimental pro- cedures not covered by ASTM standards (5) or those of special interest are discussed in the following sections. 4.2.1 Deleterious Particles in Coarse Aggregate. Michigan Department of Transportation methods (35) were used to evaluate the percentage of aggregate particles con- sidered detrimental to concrete quality and durability. In this method, all aggregate particles retained on and above the 3/8 inch sieve during gradation testing are visually inspected for a determination of aggregate type. Percentages of deleterious particles are based on the fractional weight of total aggregates used in the analysis. Using this method for recycled PCC aggregate, the total weight of crushed PCC particles containing any evidence of an exposed deleterious aggregate was included in the calcu- lated percentages. The major concentrations of deleterious substances in Michigan natural aggregates are chert and soft particles including friable sandstone, siltstone, shale, ochre, and clay ironstone. 86 Table 4-9. Michigan Gradation Limits for Coarse Aggregates Used in PCC Mixes for Pavement - Cumulative Percent Passing. (Source: 1979 Standard Specifications for Construction - Michigan Department of Transportation) Michigan Sieve Series Class 1-1/2” 1" l/2" #4 LBW 6 A 100 95-100 30-60 0-8 1.0 max.* *Loss by washing of 2.0 percent permitted for material pro- duced entirely by crushing rock, boulders, cobbles, or slag. 87 m.m ou om.N MIC OHIO OMIoH mnIom mNImm mmImc ooHImm OOH mZN Em and oo~§ om§ om* oafi w* c* :w\m nonsbz oumwoumm< Acowumuuommcmuh mo unmauummoa amwwflofiz I cowuoduumcoo How mcowuwowmwooam pumpcmum mnaa "mousomv .mawmmmm unmoumm o>HumHnBDU I mucoew>mm 00m Mom max“: a« mom: moumwmnww< oawm Mom muwawq nowumpmnu Suwanee: .OHI¢ oHan 88 hangaoo Ho>muu paw pamm Hana vcmm Hmuaumz mz~ mammaou Ho>muo was vcmm ammuoz Ho>muw Hmnaumz <0 HmumxcH NHIms muouocoo maocaabuwn nonmauo m < oumwonwwm nu“? mvmfi mumhocoo no umou BuseImNmmHm I auoumuonma memos pwnmnuo a aOmxth quH zmauo>o :m spas mouoo poemsuu HID aomxomh dmIH mouoo nonmnuo o xomuu oauumm Am quH mmuoo pmnmauu m nomvsm 3oz omIH mouoo nonmauu HI< compnm 3oz oaIH maowuoom anm nonmauu < condom cowumwuommn mpoo oumwmuww< .mouwwouww< soumomom Mom cofiumauomaH mousow use wcwpoo .HHIq canoe 89 4.2.2 Bulk Specific Gravity and Percent Absorption of Coarse Aggregate. In order to provide a comprehensive investigation of these prOperties in recycled PCC, tests were made on each size fraction of Coarse Aggregate A. Test results were weighted on the basis of average percentage retained on each sieve size using the following formulae (5): ch = 1 (4-1) P1 + P2 + + + P" 1006, 10062 lOOGn where: G1, G2, ... Gn = Appropriate specific gravity values for each size fraction; P1, P2, ... P" = Weight percentages of each size fraction present in the original sample. and: Ab=£fii+§2fl+++§n§n (4-2) 100 100 100 where: A1, A2, ... An = Absorption percentages of each size fraction in the original sample. Test results for each size fraction are shown in Table 4-12. A visual examination of the aggregates at each sieve size resulted in a determination that the tOp-size material contained a larger proportion of unbonded and crushed natural aggregate than the material retained on the smaller sizes. 90 Table 4- 12. Weighted Bulk Specific Gravity (Cb ) and Percent Absorption (Ab) of Recycled PCC Coarse Aggregate A. Sieve Percent Retained Gb Ab l” 2 2.52 2.54 3/4" 22 2.36 3.98 1/2" 33 2.34 4.50 3/8" 18 2.29 5.34 #4 25 2.23 6.50 Weighted Average 2.31 5.00 91 The aggregates retained on the #4 sieve were mostly crushed mortar particles. 4.2.3 Salt Content (NaCl) of Portland Cement Concrete. Because the Michigan Department of Transportation uses large amounts of rock salt as a deicing agent for highways, there was a concern that detrimental amounts of sodium chloride may have infiltrated the PCC material used for re- cycling. Test methods used by the Michigan Department of Trans- portation (20) to determine damaging amounts of salt, in pounds per cubic yard, in bridge deck concrete were con- sidered appropriate for this research. Michigan specifies that when the salt content of bridge deck concrete exceeds four pounds per cubic yard, the con- crete should be removed and replaced with new concrete. In- asmuch as test results (Table 4-13) for the recycled PCC used in this research were well under the specified amount, this factor was not considered significant. This is espe- cially true considering that the transverse joints in the pavement slabs (Aggregate A) would contain the highest con- centrations of salt. 4.2.4 Experimental Results for Aggregate Properties. The reSults of various experimental rests for all re- search aggregates are shown in Tables 4-14 through 4-16. Test results are compared to Michigan Department of Trans- portation specifications where applicable. 92 Table 4—13. Salt Content (NaCl) of Recycled PCC Aggregates. Aggregate Code NaCl, lb./yd3 A* 1.89 A-l 1.72 1.72 C 1.72 D 1.03 *Average of three samples. Table 4-14. 93 Deleterious Particles in Coarse Aggregates Used for Research Compared to Michigan Department of Transportation Specifications. Percent Soft Percent égggegate Code Particles Chert Sum A* 0.7‘ 0.5 1.2 A-l 0.6 0.5 1.1 B 1.5 1.0 2.5 C 1.3 2.9 4.2 C-l 0.9 0.8 1.7 D Negligible Negligible --- E Negligible Negligible --- 6A 2.4 4.3 6.7 MDOT Specifications 2.5 max. --- 9.0 max. *Average of three tests. 94 .mGOfiumoHMHooam unmanao ca pmwmwomnm uoz I man ou Howumx III IIII IIII «xmfi o.NH mnowumowm«oomm Hon: qoa no.~ No.a o.m <0 III wm.~ q¢.H III H mm HH.~ om.w ¢.o 9 III oq.N wu.~ III HID III mm.~ m¢.m 0.0 0 III om.~ wN.¢ o.~ m III mm.~ m¢.q q.H HI< on Hm.~ oc.m m.o < swam? ream“... gawk... Ina... saw... was: xaam unmoumm unmouom .soumommm wow wow: mmumwmuww< omumoo mo mmwuummoum maowum> .mHIq canoe 95 .mfiOHumoHMHoomm ucmuuao aH poHMHoomm uoz I mmmH ou HoHumxs .mumHa monouomou pumvcmum oco Honaba mnu Home: HHos muo3 mmHuHHDQBH oHGmeo Mom mumoa * .xma m IIII IIIII *xxma o.oH msoHumoHMHummm Hon: N om.~ mm.H H.n mz~ II mN.N o¢.~ III m «H oo.N on.HH n.m a II mN.~ NH.m III HIU RH mH.~ mm.n 0.5 0 RH m~.N NH.N m.m m kH mH.N wn.m m.o HI< *H 0H.N Hm.w m.w ¢ umnaaz Aaov aua>muu Aaav anon «woo mumHm UHMHooam GoHumHomn< mmoncaom mumwouww< oHGmwuo MHnm unmoumm unwoumm .noumommm pom pom: moumwouww< och mo moHuuomoum m50HHm> .oHIq mHamH 96 Coarse aggregates produced by crushing Portland cement concrete were superior to the control natural gravel in those tests designed to evaluate the possible effect of aggregate properties with respect to the durability of con- crete. Recycled PCC fine aggregate properties were essen- tially comparable to the durability properties of the con- trol natural sand. The extremely high absorptions and low specific grav- ities of Aggregate D are assumed to result from the fact that the aggregate particles were, mainly, crushed mortar containing progressively higher percentages of entrained air. CHAPTER V CONCRETE PROPERTIES Experimental procedures to determine the properties of fresh and hardened recycled aggregate concrete, as well as for control mixes, were accomplished according to the follow- ing standards: 1. Air Content of Freshly Mixed Concrete by the Volumetric Method - ASTM C 173-78. 2. Capping Cylindrical Concrete Specimens - ASTM C 617-76. 3. Compressive Strength of Cylindrical Concrete Specimens - ASTM C 39-72. 4. Concrete Test Specimens, Making and Curing in the Laboratory - ASTM C 192-76. 5. Flexural Strength of Concrete (Using Simple Beam with Center-Point Loading) - ASTM C 293-68. 6. Fundamental Transverse and Torsional Frequencies of Concrete Specimens - ASTM C 215-60. 7. Resistance of Concrete to Rapid Freezing and Thaw- ing - ASTM C 666-77. 8. Slump of Portland Cement Concrete - ASTM C 143-74. 9. Unit Weight and Yield of Concrete - ASTM C 138-77. 97 98 5.1 Aggregate Proportions for Experimental Mixes The main emphasis of this research was to determine the effects of using the various components of recycled aggregates, resulting from crushing surfacing concrete found in existing pavements, on the properties of concrete and pavement design. In this respect, research aggregates were prOportioned on the basis of crushing pavement concrete peculiar to actual field conditions. 5.1.1 Regycled PCC Aggreggte As a result of determining the prOportions of fine and coarse aggregates required for mix design compared to the percentages of these aggregates resulting from the crushing process, it was determined that approximately 30 to 35 per- cent of the fine aggregate, necessary to utilize all of the coarse aggregate produced, would be available in the crusher fines. Therefore, additional fines in the form of conven- tional aggregate would have to be provided. Since it was previously determined that the coarse and fine fractions of recycled PCC aggregate should be split and stockpiled separately to avoid segregation problems, a number of Options concerning the ratios of recycled and natural fines used in mix proportioning were considered. These options could range from using all crushed PCC fines to all natural fines in combination with 100 percent crushed PCC coarse aggregate if concrete quality permitted. Recycled Aggregate A from the crushed slab sections was used, extensively, as a standard for experiments to 99 determine concrete properties related to varying the pro- portions of recycled PCC crusher fines with conventional fines. Crushed Pavement Cores and Test Beams Individual concrete batches made with aggregate result- ing from crushing PCC pavement cores were used as a check against the standard mix. Concrete made with aggregate from the crushed laboratory beams provided an initial investiga- tion to determine if concrete made with recycled aggregates could be recycled again in the future. Percentages of the volumes of coarse and fine aggre- gates used in the recycled PCC concrete mixtures are identi- fied by batch series and aggregate code in Table 5-1. 5.1.2 Recycled PCC in Combination with Bituminous Concrete Because of conflicting reports concerning the detri- mental effects of overlayment materials on concrete quality (3) and the entrainment of air in fresh concrete (3,19), mixes were designed incorporating various amounts of crushed bituminous concrete. Bituminous concrete overlays in Michigan are normally 1-1/2, 2-1/2, and 4 inches in depth. Calculated on the basis of these overlay depths on a nine inch PCC pavement, volume percentages are 14.3, 21.7, and 30.8 percent respec- tively. Volume percentages of aggregates used in concrete batches made with combinations of crushed bituminous and PCC materials are shown in Table 5-2. 100 OOH mzN III II OOH <0 tz Houucou I OH OOH mZN III II OOH O m OOH mzN III II OOH O m OOH mzN III II OOH m 5 mm mzN 0N HI< OOH HI< 0 OOH mzN III II OOH < 0 mm mzN 0N < OOH < c On mzm 00 < OOH < m 0N mzN mm < OOH < N III III OOH m OOH < H mESHo> mOoO Iwmmwmw oOoo oabHo> opoo ucoonom oumwonww< unmoumm oumwmuww< unmoumm oumwmuww< mmHHom noumm mumwmuww< mch mumwonww< mmnmou cmeoO tz Dom OoHoxomm wow wow: moumwouww< mo mGOHumcHnaoo .HIm oHan 101 .ummu GOHumOmnw Eoum OmcHanoumO muoaocoo msocHESHHn ufioohom NH aHoumEonumm oOoO maflHo> opoo oabHo> opoo oasHo> mpoo unmoumm .ww< udmonom .ww< unmouom .ww¢ unmoumm .ww< moHHmm oumwouwwm och mumwouww< omumoo noumm .ououoaou muocHasuHm wchdHocH GwmeO RH: 00m OoHoxomm pom womb mummouww< mo mGOHumcHnEoo .NIm oHan 102 Batch series 11 and 12 were designed to test the effect of bituminous materials on air entrainment, therefore, bitu- minous fines were combined with natural fines, only, so that the possible effects of PCC fine aggregate on air entrainment are deleted. This combination would not be present under normal field conditions. Batch series 18 using 100 percent crushed bituminous concrete was designed for informational purposes only. The concrete mix designs discussed in this section pro- vided the basis of an initial investigation of the properties of concrete containing the stated proportions of aggregates and were not intended as part of a comprehensive study. 5.2 Laboratory Procedures for Test Batches. The procedures to prepare, proportion, weigh, and mix materials for concrete test batches closely followed those outlined in ASTM C 192-76. 5.2.1 Material Weighing and Preparation. Coarse aggregates were prOportioned on the basis of the average percent retained on the various sieve sizes from gradation tests for Aggregate A (Table 5-3). Weights for each size fraction were corrected for moisture content and weighed cumulatively. In order to assure complete absorp- tion, the individual aggregate sizes were recombined in tared containers and immersed in water for a minimum of 24 hours. Prior to use in a mix, excess water was decanted, the aggre- gate reweighed, and apprOpriate corrections made for mixing water . 103 Table 5-3. Average Percent Retained on Each Sieve Size For Aggregate A. Sieve 1" 3/4" 1/2" 3/8" #4 Percent Retained 2 22 33 18 25 Fine aggregates were proportioned in their original gradations. After weighing, enough water was added to the material to allow for absorption. The same procedure as that used for the coarse aggregate was followed before us- ing the material in a concrete mixture. Both the cement and mixing water were proportioned by weight. 5.2.2 Research Mix Design The basic concrete mix design used for all experiments is outlined in Chapter III. The following factors were held constant: 1. water-Cement Ratio (W/C) = 0.43 2. Cement Factor, per cubic yard = 6 sacks (564 1b.) 3. Coarse Aggregate Workability Factor (b/bo) = 0.72 4. Percent Entrained Air (1) = 5.5 i 1.5 A standard laboratory batch size of 1.4 cubic feet was sufficient for fresh concrete tests and for making the necessary test specimens. This batch size provided for 15 percent extra volume for uniformity in sampling and waste. Concrete used for slump and unit weight determinations was 104 remixed with the batch and used for test specimens. 5.2.3 Mixing Experimental Batches Concrete batches were mixed in a laboratory pan mixer (Figure 5-1) large enough to mix an entire batch. The pan and mixing blades were "buttered" before the introduction of batch material to allow for the loss of any mortar adher- ing to the mixer. The sequences stated in the standards (5) for the introduction of materials and mixing times were followed as closely as possible. 5.3 Properties of Fresh Concrete. Tests to determine slump, air content, yield, and tem- perature were made for each experimental batch upon comple- tion of mixing. A Soiltest Roll-a-meter (Figure 5-2) was used for determining air contents because of the relatively high absorptions of the recycled PCC aggregates. 5.3.1 WOrkability Although the workability of fresh concrete is difficult to define unless this factor is determined under the field conditions in which the concrete is to be used, an attempt was made to identify the finishing and consolidation pro- perties of recycled aggregate laboratory mixtures. Inas- much as the equipment used in a normal paving operation would include combinations of multiple vibrators, floats, and screeds capable of consolidating and finishing harsh con- crete mixes, laboratory observations are of minimal value. 105 Figure 5-1. Laboratory Pan Mixer Figure 5-2. Roll-A-Meter for Volumetric Air Tests 106 5.3.2 Test Results for Fresh Concrete Average test results and observations related to the properties of fresh concrete made with recycled PCC and control aggregates are shown in Table 5-4. The properties of mixes containing proportions of crushed bituminous con- crete are shown in Table 5-5. Table 5-6 shows the relationship of the percentage of entrained air to varying amounts of air entraining admix- ture added to concrete mixes containing bituminous material. It was determined that concrete containing the stated mater- ials will react normally to the addition of air entraining admixtures as indicated in Figure 5-3. 5.4 Properties of Hardened Concrete Test specimens to determine the properties of hardened concrete were made from each experimental batch in the quan- tities shown in Table 5-7. A total of 380 individual tests were completed to provide comprehensive research data. 5.4.1 CuringgTest Specimens Test specimens were removed frmm the molds the day following mixing the concrete and stored in saturated-lime water for seven days. Specimens not subject to 7-day test- ing were stored in an approved moist room (5) until tested. .coHumauomaH you OmODHonH I m<.O u O\3 I wound wcH£oummk«« .auaaanmxuoz no xomnu a you on.o I on\n ecu 00.o I u\3II .ucoucoo HHm mom Omuoounoo k 107 OooO .OooO 0.OI ~.0muOItz Hohucoo 0000 0009 H.OI m.mmH NB 5.0 . . m.H <0 Aoumuocoo OmHonomv mammm smeeIonooum mnoumuoan Ooou vooO 0.OI «.HOH 00 m.m O.H <0 Oooo poou m.OI H.Oummno Iuamaw .uwz use: .asms ua< a macaw sebum .oumwmumw< Dom OoHohomm SOHB mum: mumhoaoo ammum mo moHuHomoum .O msoaHfisuHm nuH3 mouoo Omnmsuo mwoumuoan voou SmHmm O.HI 0.0mH <5 O.< O.H <0H Oooo Ooou <.OI <.OO mo uommmm mnu ocHahouoO oH I ououocoo mquHBSuHm OmSmsuO was .Ocmm Hmuaumz .manm Ooamano OHmHm GOHumOHHomcoo wdHanch 5 .0H mo unmucou mosocH .uaoOH 3:39:03 8588 1.33» 4&3 ”...:5 $8.... .3... .5 98$ :38 .muouocoo maoaHaauHm Oonmnho paw 00m OoHohomm mo maoHuwcHnaoo nuHs opmz ououoaoo smoum mo moHuuoaoum .mIm oHAMH 109 Table 5-6. Air Contents of Concrete Made with Proportions of Recycled PCC and Bituminous Concrete. Batch Vinsol* Air Identification fi Resin Content 11A 30 8.2 11B 10 4.8 110 15 6.8 12A 20 7.7 *In cubic centimeters per 1.4 cubic foot batch. Table 5-7. Number of Test Specimens Made for Each Experimental Batch. Quantity Type Purpose 5 3 X 4 X 16 inch beams For flexural strength tests, freeze-thaw tests, and the determination of dynamiC‘moduli. 6 4 X 8 inch cylinders For compressive strength test . 110 3_. 7_. as H <2 8 z: 6_. H a5 94 2: m [—4 2: a: 2 n: 5 c. l L J l 10 15 20 25 30 VINSOL RESIN, cm3. Figure 5-3. Air Contents of Concrete, Containing Propor- tions of Crushed Bituminous Concrete for Aggregate with the Addition of Various Amounts of Air Entraining Admixture. 111 5.4.2 Compressive (fé) and Flexural (MR) Strengths Concrete test cylinders and beams were tested at 7 and 28 days. Test results are shown in Tables 5-8 and 5-9 where: f; = P/A (5-1) where: P = Total load at failure, 1b.; A = Cross sectional area of the cylinder, inz. and: MR = 3Pl/2bd2 (5-2) where: 1 = Span length, in.; b = Average width of beam specimen, in.; d = Average depth of beam specimen, in. Standard deviations for 28 day strengths were within an acceptable range for concrete tests. The relationship of the various ratios of recycled PCC and natural fine aggregates used in the standard mix to con- crete strengths are illustrated in Figures 5-4 and 5-5. Both cases indicated that maximum strengths were achieved when re- cycled PCC was incorporated as part of the total fine aggre- gate in a concrete mixture. The Michigan Department of Transportation specifies minimum 28-day compressive and flexural strengths of 3500 psi and 650 psi, respectively, for pavement concrete design. 112 .aoauwahomcw How wowsaocH u 0¢.0 u U\3 n Hohum wcwnoumm «« .hufiawnmxHoB co xomno m mom 05.0 n 0 n\n 0cm 06.0 n o\3 « 05 000 000 00a 00N0 0~0¢ mu<0H Hm>muw u was Houucou .. 000 0H5 --- 0500 ommq <0 nououocoo wmao>ommuomv mammm zwnhnmumoum huoumuonmq nu 050 005 nun 0~00 000a <0 nu 050 005 nun 00H0 05¢¢ <5 u- 050 000 --- 000¢ 0HHO *¥<0 monou wasmsuo mwoumuonmg 00 000 0H5 oqa 0H0q 00H¢ on0u<0 0¢ 000 005 000 0550 000¢ 0u0n<¢ 0N 0¢0 005 0H0 0000 0000 Uu0uo0 .0u0 0W0 00 man 5 .>00 .0um haw 0N \N00 5 .unmvH noumm Hum;¢£uwdmuum amusxmam Hmm,.£uwconum m>wmmmumaoo .oumwouww< Houucou was com ficaohoom zufiB mwmz mu¢HoCoo mo mnuwcmuum Hmnsxmam 0cm o>fimmoumaoo .m-m magma 113 nu 050 0H0 nnn 00AH 0¢0 <0H cowumauomaH How woumoe u oumuoaoo moocHESuwm 0onmsho nn 0q5 0¢0 nun 000¢ 0000 <5H meuo>o moonwafluwm suwz mouou 0m£mono Nnoumuonmq nu 0H0 000 nun 0HHO 0¢0N <0H un 005 000 nnu omaq 0000 <00 nu 055 000 nnn 00H¢ 00H0 <¢H un 005 000 nun 005¢ 00H¢ <0H wuouocoo moonwasuwm 0am manm 0m5msuu waoflm nn 000 0¢0 nun 0000 0000 o mo uommmm onu mcHEhmuoo 0H n mumuocoo mnoaflaouwm 0m£msuo 0cm «camm Hmunumz .mnmam 0m£mnuo UHmHm .>ma .eum sue mN sue a .uaouH acumm .>ma .eum awe mm was a Hmmn.£uwwmuum Hmuaxmam 0mm .Suwaouum o>wmmmhmaoo oumhoaoo moonwanuwm 0am 00m floaokoom mo Gowuwcwnaoo m suwz own: mumuoaou mo mSuwcoHum Hmudxmam 0am o>fimmoumaoo .0n0 manme 6000 5500 4500 28-DAY COMPRESSIVE STRENGTH, psi. Figure 5-4. 114 l l 25 50 Control Aggregate Concrete ,/ l L 75 160 RECYCLED PCC, percent The Effects of the Percent of Recycled PCC Fine Aggregate, in Total Fine Aggregate, on Compressive Strength. 900- 5 ‘ Control Aggregate Concrete 700- J 28-DAY FLEXURAL STRENGTH, psi. l J l I O 25 50 75 100 RECYCLED PCC, percent Figure 5-5. The Effects of the Percent of Recycled PCC Fine Aggregate, in Total Fine Aggregate, on Flexural Strength. 116 5.4.3 Sonic Testipg. A Soiltest CT - 366C Sonometer (Figure 5-6) was used to determine the fundamental transverse and torsional fre- quencies of test beam specimens from each experimental con- crete batch. In this test, a specimen's mechanical resonant frequency is determined by driving it with sound vibrations from a known frequency source and varying the frequency until a resonant condition is achieved. Durability Factor (DF) Test beams were exposed to 300 freeze-thaw cycles in accordance with Procedure B stated in ASTM C 666-77. This procedure specifies that the test specimens must be com- pletely surrounded by air during the freezing phase of the cycle and by water during the thawing phase while in the freezing-and-thawing apparatus (Figure 5-7). The dura- bility factor is calculated from: P = (nnzlnz) X 100 (5'3) '1! Q l - Relative dynamic modulus of elasticity after c cycles of freezing and thawing, percent; n = Fundamental transverse frequency at 0 cycles of freezing and thawing; n1 = Fundamental transverse frequency after c cycles of freezing and thawing. Figure 5-6. Soiltest CT 366C Sonometer. Figure 5-7. Freeze-Thaw Chamber. 118 and: DF PN/M (5-4) where: DF Durability factor of the test specimen; P = Relative dynamic modulus of elasticity at N cycles, percent; N = Number of cycles at which P reaches the speci- fied minimum value for discontinuing the test or the speci- fied number of cycles at which the exposure is to be ter- minated, whichever is less; M - Specified number of cycles at which exposure is to be terminated. The Michigan Department of Transportation specifies a minimum durability factor of 20 for concrete made with vari- ous aggregates. A minimum P value of 70 and M value of 300 is also specified. The durability factors for concrete made with the recycled aggregates in this research were exceptionally high (Table 5-10). Dynamic Young's Modulus of Elasticity (E) and Poisson's Ratio (u) These dynamic values were calculated from.the funda- mental transverse and torsional resonant frequencies of beam specimens using the following formulae: Dynamic E = CW'n2 (5-5) 119 Table 5-10. Durability Factors (DF)* for Research Mixes. Batch Durability Batch Durability Series Factor Series Factor 1 99 10** 81 2 99 11 101 3 100 - 12 100 4 98 13 101 5 99 14 98 6 105 15 99 7 95 16 93 8 97 17 99 9 95 18*** 37 * Tests started at 14 days of age. ** Control Mix ***Concrete using all crushed bituminous concrete for aggregates - Tested for information. 120 where: W = Weight of specimen, 1b.; n = Fundamental transverse frequency, Hz.; C = 0.00245 L3T/bt3; L = Length of specimen, in.; t,b = Dimensions of the cross section of the beam, in., t being in the direction in which it is driven; T = A correction factor (ASTM C 215-60) and: Dynamic u = (E/ZG) - 1 (5-6) where: G = BW (n”)2; B = 4LR/gA; R = A shape factor (ASTM C 215-60); g = Gravitational acceleration (386.4 in/secz); A = Cross sectional area of specimen, inz; n"= Fundamental torsional frequency. Test results for selected specimens (Table 5-11) were in the normal range for saturated concrete. 121 Table 5-11. Dynamic Young's Mbdulus of Elasticity (E) and Poisson's Ratio (u) for Selected Research Test Specimens. Batch E,psi Batch E,psi Ident. 10X6 u Ident. 10X6 1D 4.48 0.18 10B* 5.81 0.20 2B 4.69 -—-- 11A 4.44 0.23 3A 4.97 ---- 12A 4.00 0.19 4A 5.30 0.20 13A 5.18 0.25 5B 4.87 ---- 14A 4.92 0.24 7A 5.28 0.18 15A 5.11 0.27 8A 5.55 0.22 16A 4.15 0.26 9A 4.92 0.26 17A 4.97 0.18 *Control Mix CHAPTER VI APPLICATION OF EXPERIMENTAL RESULTS Inasmuch as there was good correlation between various research test results, the experimental data is considered a valid basis for predicting the procedures required to utilize recycled PCC in practical field application. In addition, the data also provides a means for evaluating the economic and design aspects of crushing existing PCC pave- ment and using the resulting aggregate in new concrete. 6.1 Economic Evaluation Discussions and projections offered in this section are related to comparing the use of a recycled PCC pavement for concrete aggregate to furnishing new natural gravel and sand The following assumptions are made: 1. Conditions dictate that the existing pavement sur- face has to be removed and replaced. 2. The resulting broken PCC material is either hauled to a dump site or recycled. 3. The crushing operation is at the project site, at a central location, and on the same site as the concrete batch plant. 4. A ten mile dual pavement removal and replacement paving project. 122 123 5. Pavement in each direction is 9 inches thick and 24 feet wide and has temperature reinforcement. 6.1.1 CrushinngCC for Aggregate Figure 6-1 shows a schematic of a completely portable crushing operation which should be capable of handling ap- proximately 250 tons of material an hour when operating under full capacity. Problems with steel removal may re- duce production to 150 tons per hour. The estimated cost of running the crushing Operation is offered in Table 6-1. Calculations were based on average monthly rental rates and hourly operating costs (29) in ad- dition to costs for labor. It was assumed the plant would operate 200 hours each month. On the basis of this estimate and assuming a practical production rate of 150 tons per hour, a price of $2.52 was assigned to the cost of producing one ton of recycled PCC aggregate using a temporary field crushing setup. 6.1.2 Cost Comparisons Costs for purchasing and hauling conventional aggre— gates were based on an investigation of 1979 prices paid by Michigan paving contractors. Inasmuch as there are certain operations peculiar to the type of project being discussed, regardless of recycling the old pavement surface or bring- ing in new aggregate for concrete, they were not included in the comparison. These operations are: 124 Portable 30" x 48" Jaw Crusher ./ l 2’ Picker's Station 4"" 18" Conveyor-____‘fl_ 42" Conveyor __..¢—Cross Belt Magnet Portable 60" x 12' nc—Double Deck Screening Plant Portable 48" Cone" " Crusher ..___/ ____24" / Conveyor 24" Radial Stacker / \\ \ 18" Radial Stacker Coarse Fine Aggregate ——-—. .-— Aggregate Stockpile Stockpile Figure 6-1. Schematic of a Portable Recycled PCC Crushing Operation. 125 .ucmaa noumn muouoaoo ms» mewwuwso pom mawunmamn maanHm><¥ use: 000 00.0000 Acou uamm 000 00.00 00.0 00.00 0000000 0000 :00 000000000 00 00.00 00.0 00.00 uo0m>aoo .00 x :00 0003.0c000 maficmmuom 0000 «00:00 .00 x :00 000 00.00 0 00.000 00.000 0000 000000000 0a0 000000 0003 0000000 300 :00 x :00 0005000 HmBomwmuom .Hm .umou .um .umoo .H$.4Umoo unmanwaum 00005000 HMuOH 0cwumuomo Hmucmm manmuuom coaumumao wagsmsuo 00m woao%omm How mumou hauaom Umumaaumm .Hn0 oHQmH 126 Breaking and removing the existing pavement. Adding new or reworking the old base material. Corrections of highway geometries. Mixing and hauling the concrete to the project. U'IJ-‘UJNH The paving Operation. Using information gained from studying the gradation characteristics of crushed concrete and allowing for a 10 percent loss, the final crushed aggregate product should provide approximately 190 percent of the coarse aggregate and 61 percent of the fine aggregate required for concrete to replace an equal section. If all of the coarse aggre- gate is utilized in concrete, approximately 33 percent of the fines would be available from the crushed PCC. Calcu- lations are based on research mix design. Aggregate proportions for one cubic yard of concrete using recycled PCC or natural aggregates are provided in Table 6-2. PrOportions were based on utilizing all of the available crushed PCC fine aggregate. Cost differentials based on required aggregate propor- tions and current Michigan prices are shown in Table 6-3. It was assumed the salvage value of steel reinforcement would be offset by pickup or transportation charges. 6.2 Envirqgmental Considerations Assigning a quantitative value to the environmental impact of utilizing recycled PCC was difficult to accomplish. 127 000 000.0 0000 000.0 000 000.0 ---- ---- 00000000 000 00000000 nun: nuau I... I... «000 000.0 NNON 000.00 muouoaou amcowucm>aou AH mum £0 mum AH mum n0 mum unwme mabHo> u£w0m3 masao> u£w0o3 oEDHo> unwwa mEDHo> mumwouww< mcwm mumwmnwm< mammoo vamm Hm>wuw cowumwuomma 000 00000000 .aowuuom Hwavm cm wcwomamom so vmmmm a mumuocoo ucm8m>mm mo 00m» 000:0 one you mumwouww¢ 0009002 no com wmaomoom mafia: macauuomoum mumwmuww< .Nuo vague 128 Table 6-3. Cost Comparisons for Aggregate Alternatives for a Ten Mile Dual PCC Pavement Removal and Replacement Project- Based on 1979 Michigan Prices W Conventional Recycled PCC Description Concrete Concrete Hauling waste concrete from the job site $175,016 $ 68,904 Disposal Charges 68,904 ------ Aggregate Costs: Gravel 249,110 ...... Sand 56,602 28,354 Recycled PCC (Production Cost) ------ 192,931 Hauling new aggregate to the job site 193,858 50,470 Subtotal $743,490 $340,659 Value of excess recycled PCC course aggregate over production costs ------- 46,376 _TOIAL| % . $743,490 $294,283 129 This was due to the absence of overall measurement standards. One standard which could be considered was the total energy required for various aggregate alternatives. 6.2.1 Energy Requirements Estimated fuel usage and other energy consuming fac- tors were converted to British thermal units (BTU) to com- pare the energy requirements for using recycled PCC or conventional aggregates in the volume of concrete necessary to replace the pavement on the design project. Conversions were based on accepted standards (21) or calculated from values furnished by Michigan paving contractors. Concrete mix designs are identical to those discussed in Section 6.1.2. Energy comparisons for gravel and recycled PCC concrete are shown in Table 6-4. 6.2.2 Natural Resources Needless to say, substituting recycled PCC aggregates for conventional natural aggregates does conserve a de- pletable natural resource. Many natural aggregate sources are already depleted and, when a new source is found, it is virtually impossible to start a new production facility due to a variety of governmental restrictions. In addition, using recycled aggregate eliminates the possible necessity of locating a suitable waste disposal site which is, also, a highly restrictive undertaking. The design project, alone, would have required the disposal of 70,400 cubic yards of broken concrete if not recycled. 130 Table 6-4. Energy Requirements for Aggregate Alternatives for a Ten Mile Dual PCC Pavement Removal and Replacement Project J Energy, BTU X 106 Conventional Recycled PCC Description Concrete Concrete Hauling waste concrete from the job site. 5097 850 Disposal Operation 340 --- Aggregate Production: Gravel 1068 --- Sand 566 284 Recycled PCC* --- l302 Hauling new aggregate to the job site. _6114 1165 TOTAL 13,785 3601 *Energy required for excess recycled aggregate not included. 131 6.3 Pavement Design Pavement thickness design using test results from the standard research mix series for recycled PCC concrete, was based on Michigan Department of Transportation design practices. Determinations were compared to AASHO (1) requirements. 6.3.1 Concrete Properties Related to Pavement Design Although the center-point loading used in this research for the determination of concrete flexural strengths may produce slightly higher values than the third-point load- ing (40) used for the AASHO Road Test, the differences were considered insignificant. An average Young's modulus of elasticity of 4.2 X 106 psi, based on static compressive tests, was used to design the AASHO nomograph for thickness design. Inasmuch as the dynamic tests used to determine values for this research may result in a 20 percent error (44), a direct use of the nomographs was considered valid. 6.3.2 Thickness Design Criteria The Michigan Department of Transportation uses an average working value of 200 pci for the modulus of sub- grade reaction (k). This value is based on a specified minimum.of 10 to 12 inches of granular subbase required over clay soils (8). Minimum pavement slab thickness is 8 inches and the maximum is 10 inches. Pavement thickness 132 is assumed and checked against the thickness determined by using the nomographs in the AASHO Interim Guide (1). Table 6-5 shows pavement thickness design requirements for research mixes according to the following: 1. Design period - 20 years. 2 k = 200 pci. 3 20 year 18-kip ESAL = 10 million. 4. Pt = 2.5 5 ft = 0.75 X MR 6 MR = 650 psi minimum. 6.3.3 Alternate Working Stress (ft) Determination The AASHO Interim Guide (1) suggests that an alternate method of determining the working stress of concrete may be accomplished by applying a statistical adjustment to flexural strength data. This method provides a safety factor for pavement design. Working stress is calculated by: ft = M - Com (6‘1) where: ME = Mean flexural strength, psi.; om = Standard deviation of flexural strength tests, psi; C = 2.326 for a 99 percent confidence level. This formula was used to check the working stress values used for research pavement thickness design. The results shown in Table 6-6 indicate a more than adequate factor of safety for the recycled PCC concrete. 133 Table 6-5. Pavement Thickness Design Based on Standard Research Mix Designs. w —"= Batch Flexural Working AASHO Michigan Series Strength,psi Stress,psi Design,in. Design,in. l 730 550 9.25 10.00 2 755 565 9.25 10.00 3 840 630 8.50 10.00 4 865 650 8.50 10.00 5 805 605 8.75 10.00 9* 865 650 8.50 10.00 10** 850 640 8.50 10.00 * Re-Rec cled PCC Mix. **Contro Mix 134 ome oqe on one o0 nun one nu new m nN0 noe nm now n oe0 one e0 new 0 oe0 one nN oem n nme nen nm nn0 N nme onn oq omn 0 vogue: eonumz ommm< 0mm .oo0u00>mo 00m .nuwcmuum 0000mm 0mO0um0umum mwmno>< enmeomum 0muoxm0m aoumm 0mm .mmouum wa0x003 .moxflz Soummmom How mmmuum wa0xuoz mo mcoHumGHEHmumo munchou0< .eue o0nma CHAPTER VII SUMMARY AND CONCLUSIONS Previous investigators predicted lower strengths when using recycled Portland cement concrete aggregates in a con- crete mixture compared to concrete made with conventional control aggregates. However, one must be aware there will invariably be strength differentials when comparing concrete made with various conventional aggregates. In Michigan for example, concrete is normally made with natural sand for the fine aggregate, and either natural gravel, lime- stone, or blast furnace slag for the coarse aggregate. Al- though these aggregates are used on an equal design basis, the resulting concrete properties cover a range of values. The prflmary criterion for acceptability is that concrete, made with an aggregate from a particular source, must meet minimum standards. Experimental results for this research indicated that aggregates produced by crushing Michigan PCC pavements were equal in quality to conventional aggregates. 7.1 Discussion of Experimental Results All research concrete mixtures, proportioned with re- cycled PCC coarse aggregate and various ratios of natural sand and recycled PCC fines, exceeded minimum design stand- ards. Within a certain range, combinations of recycled 135 136 fines and natural sand produced concrete with higher strengths than for concrete made with control aggregates. As with the results reported by others, recycled PCC con- crete made, exclusively, with either conventional or re- cycled fine aggregate produced lower strengths than control aggregate concrete. Nevertheless, strengths were apprecia- bly higher than minimum Michigan requirements (35). Initial experimental data resulting from incorporating various proportions of crushed bituminous concrete in the recycled concrete mixtures indicated no serious detrimental effects when this material was used as a percentage of the coarse aggregate. Significantly lower strengths were expe- rienced with the addition of crushed bituminous fines. These fines are almost totally coated with bitumen and may, therefore, have to be considered as voids in a concrete mixture when designing for strength. Inasmuch as the properties of bituminous materials are susceptible to various temperature ranges (l4), and since the experiments in this research were conducted under prescribed laboratory temperature conditions, a valid anal- ysis of the total effects of incorporating this material in a Portland cement concrete mixture is not within the scope of this investigation. In all experiments, regardless of the prOportions of aggregates used, concrete made with the recycled PCC re- search aggregates exhibited durability prOperties superior to those of concrete made with normal conventional aggregates. 137 7.2 Conclusions The Michigan Department of Transportation has used qualitative methods of designing and proportioning Portland cement concrete since 1928 (31). Therefore, one can assume there are high quality materials in a major portion of the State's existing PCC highway pavements. Usual reasons for pavement removal are due to mechanical failures resulting from subgrade, drainage, or joint problems. However, the methods formulated in this research, for experiments with pavement cores, provide a systematic means of predetermin- ing the properties and mix design requirements of aggregates resulting from.recycling any existing PCC material source. There is a high degree of assurance that the result of using these methods will equate to actual field crushing and design requirements. One of the most interesting aspects of this research was the experiments involving the recycling of recycled PCC concrete. Test results for both aggregate and concrete properties furnished information this re-recycled aggregate was high in quality and durability. -Therefore, one may project that existing PCC pavements, in addition to pro- viding an aggregate source for the future, will continue to generate an adequate supply of aggregates for pavement re- placement after once being recycled. Another point of interest is that recycling an exist- ing pavement produces about 150 percent of the total aggre- gate volume needed for the concrete required to replace the 138 section removed. Therefore, additional high quality aggre- gates will be available for such construction purposes as concrete shoulders, concrete barriers, necessary concrete pavement widening, subbase aggregate, and a variety of other uses. Although the concrete mix designs used for experiments in this research are related to utilizing recycled PCC aggre- gates for pavements, there is strong evidence this material would provide an excellent aggregate for concrete used in bridges, buildings, and other structures. Before utilizing recycled PCC aggregates for structural purposes other than pavements, additional research would be necessary to eval- uate aggregate and concrete properties related to the intended use. The resulting determination of this research is that utilizing recycled PCC aggregates for Portland cement con- crete offers a viable alternative to conventional aggre- gates on an equal design basis. This is especially true for recycling an existing PCC pavement where significant cost savings and energy conservation can be realized. Additional experimental investigations, covering the range of variables associated with incorporating re-recycled PCC or proportions of bituminous concrete in concrete mix- tures, would be necessary to determine the validity of initial research results using these materials. LIST OF REFERENCES 10. 11. LIST OF REFERENCES AASHO Interim Guide for Design of Pavement Structures, American Association of State Highway Officials, Washington, D.C., 1972. Bauer, E.E., Plain Concrete, McGraw-Hill, New York 1949. Bergren, J.V. and Britson, R.A., Portland Cement Concrete Utilizing Recycled Pavement, FHWA - DP-47-1, U.S. Department of Transportation, Arlington, Virginia, September, 1978. Buck, A.D., "Recycled Concrete", Hi hwa Research Record No. 430, Highway Research Board, I973, pp. Il8. "Concrete and Mineral Aggregates", 1978 Annual Book of ASTM Standards, Part 14. "Crushing Converts Rubble Into Subbase Aggregate", Roads and Streets, May, 1971, pp. 44 and 45. Design and Control of Concrete Mixtures, Portland Cement Association, Skokie, Illinois, 1979. Field Manual Of Soil Engineering, Fifth Edition, Michigan Department of’State Highways, Lansing, Michigan, 1970. Fordyce, P. and Teske, W.E., "Some Relationships of the AASHO Road Test to Concrete Pavement Design", Highway Research Record No. 44, Highway Research Board, 1963, pp. 35-70. Fordyce, P. and Yrjanson, W. A. "Modern Design of Concrete Pavements" , Tran ortation Engineerin Journal of ASCE Vol. 95Q,§§o. 3, August, 19%é, pp. 407- 438. Frondistou-Yannas, S. and Itoh, T., "Economic Feasibility of Concrete Recycling", Journal of the Structural Division, Proceedings Of the American’Societ of Civil En ineers, Vol. 103, No. 3T4, April, 1977, pp. 88§-899. 139 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 140 Frondistou-Yannas, 8., "Waste Concrete as Aggregate for New Concrete", ACI Journal, August, 1977. pp. 373-376. Gluzhge, P.J., "The Work of Scientific Research Institutes", (From Gidrotekhnicheskoe Stroitelstvo, No. 4, April, 1946, pp. 27 and 28), The Engineer's Digest, Vol. 7, No. 10, 1946, p. 330. ‘ Hong, H., "State of the Art" Theory and Application of Sonic Testing to Bituminous Mixtures", HRB Special Report No. 94, Highway Research Board, I968. Hudson, R.G., The Engineers' Manual, Second Edition, Wiley & Sons, New York, 1961. Hudson, W.R., "Comparison of Concrete Pavement Load- Stresses at AASHO Road Test with Previous Work", Highway Research Record No. 42, Highway Research Board,il963, pp. 57-98. "Landfill Avoids Concrete Waste by Aiding Recycling Operation", Rural and Urban Roads, March, 1978, pp. 40 and 41. Lokken, E.C., ”Recycling Portland Cement Concrete", Paper for Presentation to the UWEX-ENR Technical Institute on Recycling Pavements, New YOrk, October 25, 1978. . "Old Pavement Recycled Into New Subbase", Concrete Construction, October, 1975, pp. 441 and 442. Procedures for Determining Salt Content (NaCl) in ’PbrtlanHSCement Concrete, Michigan Department of Transportation, circa 1976. Ray, G.K. and Halm, H.J., ”Energy Savings Through Concrete Recycling”, Paper for Presentation to the Transportation Research Board, Washington, D. C., January 17, 1978. Ray, G.K. and Geesaman, J.D., "AASHO Road Test And Its Affect On Future Design Standards", Paper for Presentation to the ARBA 10th Annual National Highway Conference, Springfield, Illinois, October 1, 1962. Ray, G.K., "Recycle Old Concrete? It Can Save You Money", Highway and Heavy Construction, January, 1978, pp. 30 and 31. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 141 "Recommended Practice for Selecting Proportions for Normal and Heavyweight Concrete", ACI Standard 211.1-77, American Concrete Institute,’Detroit, Michigan, 1977. "Recycled Slab is New Runway Base", Highway and Heayy Construction, July 1977, pp. 30:33. "Recycling 640 Tons of Crushed Concrete a Day" Michigan Contractor and Builder, February 4, 1978, pp. 10 and 11. "Recycling Roads and Buildings with Portable Plants", Pit and Quarry, February, 1973, pp. 31, 92 and 106. "Recycled Rubble Saves Contractors Money", Roads and Streets, April, 1973, pp. 80 and 83. Rental Rate Blue Book for Construction Equipment, Equipment GuidelBookiCompany, Palo Aito, California, updated 1979. Sadler, T.B., "A Crushing Success: Aggregate from Concrete", Public Works, April, 1973, pp. 72 and 73. Shehan, E.L., The Mortar Voids Method of Proportion- ing Concrete as Used by Ehe Michigan Department of State Highways, Michigan Department of State Highways, September, 1970. Standard Specifications for Road_apd Bridge Construc- tion, Michigan State Highway Department, Lansing, Michigan, 1942. Standard Specifications for Road and Bridge Construc- tion, Michigan State Highway Department, Lansing, Michigan, 1950. Standard Specifications for Road and Bridge Construc- tion, Michigan State Highway Department, Lansing, Mihhigan, 1957. Standard Specifications for Construction, Michigan Department of Transportation, Lansing, Michigan, 1979. Talbot, A.N. and Richart, F.E., "The Strength of Concrete Its Relation to the Cement and Water", University of Illinois Engineering Experiment Station, Bulletin No. 136, October, 1923. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 142 Thickness Desigp for Concrete Pavements, Portland ement Associafion, Skokie, Illinois, 1966. Urquhart, L. C. et a1. Civil En ineerin Handbook, Fourth Edition, ‘McGraw-HiII, New York, I959. Vantil, C.J., et a1., "Evaluation of AASHO Interim Guides for Design of Pavement Structures", National Cooperative Highway Research Program Report No. 128, Highway Research Béard, 1972. Various, Significance of Tests and Properties of Concrete and Concrete-Making Materials, STE 169B, ASTM, Philadelphia, Pennsylvania, 1978. Vesic, A.S. and Saxena, S.K., "Analysis of Road Test Rigid Pavements", Highway Research Record No. 291, Highway Research Board, 1969. Waddell, J.J., et a1., Concrete Construction Handbook, McGraw-Hill, New York, 1968. Westergaard, H.M., "Stresses in Concrete Pavements Computed by Theoretical Analysis", Public Roads, Vol. 7, No. 21, April, 1926, pp. 25-35. Whitehurst, E.A., Evaluation of Concrete Properties from Sonic Tests, American Concrete Institute, Detroit, Michigan, 1967. WOods, K.B., et a1., Highway Engineering Handbook, McGraw-Hill, NeinOrk, 1960 Yoder, E.J. and Witczak, M£W., Principles of Pavement Design, Second Edition, Wiley and Sons, New York, APPENDICES APPENDIX A' VALUES USED FOR ECONOMIC AND ENERGY COMPARISONS 143 Values Used for Cost Comparisons in Table 6-3: Volume of concrete to be removed and replaced: 24 X 0.75 X 5280 X 20/27 = 70,400 yd’. Estimated tonnage of existing concrete at 145 1b/ft3: 27 X 145 X 70,400/2000 = 137,808 tons Conventional Concrete Hauling broken concrete from project to dump site: 15 mi 0 $1.27/ton. Hauling gravel and sand to project: 25 mi @ $1.78/ton Disposal charges: $0.50/ton Aggregate costs: Gravel $3.50/ton Sand $1.50/ton Aggregate required: Gravel 2022 X 70,400/2000 Sand 1072 x 70,400/2000 71,174 tons 37,734 tons Recycled PCC Concrete Hauling broken concrete from project to job-site crusher: 2.5 mi @ $0.50/ton Hauling sand to project: 25 mi @ $1.78/ton continued next page 144 Values Used for Cost Comparisons in Table 6-3 continued: Aggregate costs: Recycled PCC $2.52/ton (production cost) Sand $1.50/ton Aggregate required: Recycled F.A. 698 X 70,400/2000 = 24,570 tons Recycled C.A. 1477 X 70,400/2000 = 51,990 tons Sand 537 X 70,400/2000 a 18,902 tons Total recycled coarse aggregate from crusher: 137,808 X .9 X .8 = 99,222 tons Excess recycled PCC coarse aggregate: 99,222 - 51,990 = 47,232 tons Note: Hauling and new aggregate costs are based on 1979 prices for Michigan. 145 Values Used for Energy Comparisons in Table 6-4: Diesel Fuel: = 184,920 BTU/gal. Hauling aggregates and broken concrete at 5 mi/gal and 30 tons/load: 184,920/5 X 30 1,233 BTU/mi/ton Disposal operations at 2 gal/hr and 150 ton/hr: 184,920 X 2/1501 2,467 BTU/ton Natural Aggregate Production: 15,000 BTU/ton (FHWA) Recycled PCC Production: Generator at 8.8 gal/hr and 150 ton/hr: 184,920 X 8.8/150 = 10,849 BTU/ton Wheel Loaders at 5.0 gal/hr and 150 ton/hr: 184,920 X 5.0/150 = 6,164 BTU/ton APPENDIX B SAMPLE CALCULATIONS 146 omen uxmc eosa0ucoo 00.000 u 0.00 0 00.0 0 000.0 0 00. 020 .000 00.000 u 0.00 0 00.0 0 000.0 0 00. 0 .000 000.0 000.00 - 00 H00000000 .0.0 0104.0 000.0 u 00 x 000.0 ....... 000 000.0 u 0.00\00.000 00.000 u 000 0 00.0 00003 000.0 a 0.00 0 00.00000 00.000 0 00 0 0 000000 000.00 u 0.00 0 00.0\00.0000 00.0000 0 00 0 00 0 00.0 .0.0 .000 .000000 .00 4000003 0000000: .000.0 - 00 .00.0 - 00 .000 000 .000.0 - 00 .00.0 - 00 .0 000000000 00000000 000 0.0.0 m.0000 - 00 .00.0 - 0o .0 0.0.0 000 u00.0 - 00 .0.0 00000000 H000500 “Nn.n uucmucoo 00¢ 00000 e ”uouomm uamfioo ”m0.o "003 0000\00 00 "00 m00.0 "00\0 “n00 0 "000020 mo0umm soumm u cmwmmo x02 mumuocoo pom mco0um0so0mo m0ofimm 147 .QH mm.~mm u um.N¢~ + ow.m¢a .nH owqmqa .MH m~.¢ u wmao.o x mm.mqm . H .nH ¢~.Hn u ammo.o x mm.nmw .QH nm.mn u no.0 x «0.000 00003 00009 020 .000 0 .000 0.0.0 .00 "coauQMOmnm pom wmuwscmu 00003 Hmcoauauv< “UmacHucoo N mmHMwm nuumm n cmeon #02 mumhocoo How mGOHumHDono mHmEmm 148 Calculations of Constants for Dynamic E andgp - 15-1/2"*Beams: ' Can 0.00245 L’T/bta E C Radius of Gyration (K) = t/3.464 = 3/3.464 From Table I - ASTM C 215 for K/L = .866/15.5, T = 1.28. .00245 X (15.5)3 X 1.28/4 X (3)3 = 0.108 = 0.108 th = Bwn"2 4LR/gA .75 + 1.33/(4 x .75) - 2.52 (.75)2 + .21 (.75)6 = 1.286 4 x 15.5 x 1.286/386.4 x 12 = 0.017195 0.017195 W(n")2 E/ZG - 1 63 no N U! C) F1 0 II ‘6 ll Example: Beam 4-A n = 1670 n" = 2730 w = 15.323 lb. E = 0.108(15.323)(1790)2 = 5.30 x 10° psi G = 0.017195(15.323)(2890)2 = 2.20 x 106 psi. 5.30 X 105/2(2.20)(10)6 - l = 0.20 ‘C II 149 Calculations to Determine the Amount of Course and Fine Aggregates Produced in a PCC Recycling Operation: Assumptions: 10% Crushing Loss, 20% Passing #4, F.A. - Ga = 2.18, C.A. - G = 2.35, b Concrete Wgt. = 145 lb/ft’. 145 - .1(145) = 130.5 lb. 0.8 X 130.5 = 104.5 lb. Wgt/ft3 of Agg. Produced Wgt/ft3 of C.A. Produced Wgt/ft3 of C.A. Required (New Concrete) 9 55 1b. % C.A. Required = 104.5 X 100/55 = 190%. .2 X 130.5 = 26.1 lb. 26.1/2.18 X 62.4 a 0.192 fta. Wgt/ft3 of F.A. Produced Vol/ft3 of F.A. Produced 8.5/27 = 0.315 ft3.* 0.192 X 100/0.315 = 61%.* Vol. F.A. Required Z of F.A. 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