| | | | | | wIMIh sae Ill Te 1293 00871 2915 To ew cea 6 OF marr epee an aay bre WA .¥ Michigzn $*-*- INTRODUCTION The effect of hydrated lime on the tensile and ceonm- pressive strength of mortar and concrete has long been @& source of argument between Phe Portland Cement Association and the National Lime Association. In a letter submitted by Zhe Portland Cement Association they quote the following items taken from a paper entitled "Effect of Hydrated Lime and Other Powdered Admixtures in Concrete" by Professor Duff A. Abrams of the Struétural Material Research Laboratory. (1) "In general the addition of powdered materials re- duced the strength of conorete approximately in proportion to the quantity of admixture. Some exceptions are notéd below. (2) "In usuel concrete mixtures, each 1% hydrated lime (in terme of the volume of cement) reduced the compressive strength 0.5%; 1% by weight of cement reduced the strength 1.2%. Phe reduction in strength caused by replacing cemmt with an equal value of hydrated lime was about 1.75 times that caused by adding hydrated lime, (3) "High ealcium and high magnesium limes produced the game effect. (6) "Rich concrete mixes showed a greater loss in strength due to powered admixtures than the leaner ones. Lean mixes (1:9 to 1:6) and in those with aggregates graded too soarse for the quantity of cement used, the strength -ji- 96038 was little affected or slightly increased by admixtures up to 50%. (7) "The wetter mixes showed a greater loss in strength than the dry, due to the addition of hydrated lim. (8) "The effect of admixtures wes in geheral independ- ent of the age of the cement. (10) "Hydrated lime and other powdered admixtures used in these tests slightly increased the workability of the leaner mixes (1:9 and 1:6) as measured by the slump test. Ordinary mixes (1:5 and 1:4 were little affected; richer mixes (1:3 and 1:2) were made less plastic. (13) "Hydrated lime had little effect on the absorption of dry concrete, increased the evaporation of water from wet concrete and produced no beneficigl effect on the strength of concrete stored in air." Also the following is a copy of the statement, (sub- mitted to the author by letter) of T. H. Hart, Manager of Construction, Department of the Lime Association. "Hydrated lime is used in concrete for the purpose of making it work smooth, fat and buttery. It produces an effect which no emount of water can produce, and permits the use of a dryer batch than would otherwise be possible. This leads directly to greater strength, (if the water is carefully controlled) and at the same time gives a better flow thru the mixer, better discharge from the mixer, flow in chutes and hoppers, better flow around reinforcement and complicated forms; smoother white surfaces, less segregation, etc. A aPea long train of advantages are inter-related. These have never been masured mthematically. In most of the tests, the water has not been properly controlled and investigators have reported a reduction in strength which was not really eaused by the lime itself, but by the water which they added (quite unnecessarily) with the lime.” Mr. Hart makes several statements that conflict with those of Professor Abram. Mr. Hart says, ' Hydrated lime is used in conerete for the purpose of making it work smooth, fat and buttery. It produces an effect whieh no amount of water oan produce and permits the use of a dryer batch than would otherwise be possible. Professor Abram contradicts the above when he states that, "Hydrated lime and other powdered admixtures used in these tests slightly inereased the workability of the leaner mixes (1:9 md 1:6) as measured by the slump test. Ordinary mixes (1:5 and 1:4) were little affected; richer mixes (1:35 and 1:2) were made less plastic.' Mr. Hart also claims that when a proper amount of water is used the addition of hydrated lime will ease a stronger eonorete while Professor Abram states that,'In general the addition of powdered materials reduced the strength of oon- crete approximately in proportion to the quentity of admixt- ures.' Also, ‘The wetter mixes showed a greater loss in strength than the dry, due to the addition of hydrated lime.' Professor Abram's only statement in favor of lime is that it increases the evaporation of water from wet concrete. Some one must be in error and therefore it seems to be the policy of one association or the other to make ineorrect =~Zo statements for simply commerciel reasons, }-} Kase 230 275 350 10% of Lime 240. 285 as) ae 290: 356 Ac ars 2 ae Ky es) 3D | +: B40 be 91) 15% of Lime Rg B20 5 2. 275 $35 es 250 ph br 3B 116 PA 280 20% of Lime 220 260 290 ee i / ’ & wv 8 ave; BD SBT 1 yy 7 190 4:35) 275 25% of Lime Bale) 220 260 Pacey 185 290 f ! & 240 Ave; 187.5 ov bay 9 it * BIO ee 190 . B15 hy eS ai te tT) pel) : 210 225 7 rue) a oe Aves oo ead | cae TEM o-Ps BE ss Be ge Me ee) Sa teh be ele Lr am: eae ieee pe te | ) ; Brigvuet mold and Lriguet Briquetl, Testing machine All that was said about the mat cement tests applies to this test. There sre a few variations in the diagram as for instance: The 5% point on the 14th day shows a low test; while the 10% point on the 14th day shows a high test. The variations on the tensile tests have been eharged up to the personal equation, beeause the variations have not held constant for the 7, 14 and 28 day graphs. 135 Mortar Mix. The same number of test pieces with the same variation of lime were made for this test as in the neat cement and 132 mortar mix. These briquets were seasoned as were the neat cement and 1:2 mortar mix. Phe average results are summed up in the Conclusions. The results are given in Table III and comparative graphs shown on Diagram TII. What was said cf the neat cement miz and 1:2 mortar mix applies to the 1:3 mortar mix, as shown by the graph. In all the tensile tests the graph proves what Professor Abram has said and what was quoted in his paper as Item I. COMPRESSION TESTS. Two-inch cubes were mde of neat cement 1:2 md 1:5 mortar with a eross sectional area of four square inches, for compressive tests. All blocks were set up in plaster of paris before being broken to eliminate uneven surfaces. Neat Cement. Twelve cubes of neat cement of normal consistency were made for each mixj- 0%, 5%, 10%, ete., to 30%. Four were tested at the end of 7 days, four at the end of 14 days and four at the end of 28 days. The blocks were seasoned the same as the briqets. The results are tabulated in Table IV and comparative graphs are shown in Diagram IV. The graph shows a decided difference between the tests of the cubes and those of the briquets. The test of the 7 day cubes is very similar to that of the 7th day briquets and also the 14th day. The 28 day are stronger than the 14 day test pieces at 0% and 56%. Then the 28 day dropped below the 14 day; rose above at 15%; went below to 20% and continued so to 30%. The graphs show that in rich mixtures after a certain age the mortar begins to lose strength, The only way that it ean be accounted for is that on drying,the lime sets up forces that cause very small ocracks invisible to the naked eye and &s a result of the mall cracks, the strength is reduced. This is one of Professor Abram's theories. This graph not only shows that ace decreases the strength, but that Professor Abrams first item is checked again. 1:2 Mortar Mix. The same number of cubes with the same variation of lime were made for this test as were for the neat cement. These cubes were seasoned the same as the other ones. The results are given in Table V and comparative graphs shown in Diagram V. The &% tests of the 14th day is the game as 5% tests for the 28th day which shows that age de- creases the strength and ggaein the 28th day, 10% tests fall below the 14th day 10%. From here on the graph is similar 28° oT ie, ee ee a) sn ee Pe OP ree |. sa “> ae 6 tans © + ty rh et > * 4 i eee - $e Ss! wT Wel ee dea ied Se Laon nls ee 2: RAR ee tO ee ad ina, , > r er ‘ j a >Er y Ci ee eee Neg ts ea Ug ro ae Ab: a ENG ay oe. ee rer 3h 25905 Over- 25760 Poet 31000 Patan) Pape ee ele | 26725 | ta, ica Ave, ~ 5537 “CBT 16055 19775 ire 13240 Fae Oy ert ieee t's 15520 21670 ' 14680 Bey rm eo eo}: p a 11920 21850 1] ne Ee ar re PEE CVE “Slip “F210 9510 pet 10460 16260 10590 15020 ~~). = = 253 > .* — Cie i Se wi eg at ay - " Sha EPO - % ; f x. « . . 5 a7 _* a 4 SS . ~% ey = rf aks A aS as ° ag ee ~2 = Fi) ee! ee Ng tek Ns aay hs FG oe 9) 4 : : | : | ; . ; ; ‘a Diagram| No +: vies deme. (> mes) ee aa - 6% of Lime 0% of cas Sto a Fe ks) 255 of Lime 20% of Lime aE 25% of Line 30% of Lime Wote: Averages are given in pounds per*square ineh Mal MINS =- COMPRESSIVE STRENGTH oa vac oe pha: ae 4 cs aeey hg 12075 8000 9800 9850 8725 est o)s) 9000 [e100 20Or 7770 7570 Laclele Bashy é oe BES) 6750 ets Bd 5415 5540 6120 5850 CUBES - A 14 Day 12525 10925 10460 12150 oi pBeTs Obs) 12210 11595 pe Rsk: 88) ree) 10640 9545 10895 11290 wo) te) peas 08 PART hg 16720 15695 17650 16900 mse’ BAS T> @) 14105 12270 9110 10550 10525 Bless Sy As 12570 10940 11005 11745 eva) 10210 10555 10460 ofthe ors 10280 9590 0) 8) 10580 8615 eETay 9050 (were Bras eee re: oh ei uy: es EB ss Sem est 9 cL oa Fy a rok or 2 Br Berk EASES ne Wsit0) 9860 bss eee 7630. 9550 ey iss) . RS oe s PO ee re ee 6015 11025 a 6855 7950 9000 ‘ cae ave, T767 ig | ror Vat ars oe of Lime 6180 Pate) Vey aie te es os | J 5 : 3 Oe BE) To27 te | PNT) Cys Erte ee eae et 4870 6560 Veto | Evra 35) Prone cee 1:78 | Ee 8040 CT Pa eae Sin 4510 56 pa) 7295 Aart) reTte) Set) 7370 Ey T Bis 6365 __ eee 1's rere ee Ae basen } 4550 eer 6075 Peden.) Pera.) Fo ebeis Eat sss or ee ve ao Beery.) Perr Ere of Lime 3200 4070 stots) in Erte 4410 eae) aee3-7 4835 ECE oa sm x we hel ae eae ae ry Pere PL ah rere < ilaad yy et us A: ees hss te ne sal oe Diagram es ——_— = Cube mold and cube Cube resting machine to that of the briquets. The variation may be due more to the personal equation. 1:3 Mortar Mix. The same number of cabes with the same variations were used in this test as in the other tests. The cubes were seasoned as were all the other cubes. The results are given-in Table VI and comparative graphs shown in Diagram VY. This graph shows that the age is not effective as far as this test goes. This still further proves Professor Abram's first item in his paper. There ie a slight variation in the 8% and 10% eubes at 7 and 14 days, but this is due to the personal equation. CONCLUSIONS. From the tests preformed it seems proper to conclude that under no oondition does rich mixtures of mortar (neat cement, 1:2 and 1:3) with lime increase the tensile and compressive strength, but bears out the statement of Professor Abram's in which he says, ‘In general the addit- fon of powered materials reduced the strength of concrete approximately in proportion to the quantity of admixtures.' There may often be places where the value of lime for producing color, etc., will ocut-weigh the importance of high strength, but under ordinary conditions lime should be Left @ut of conorete. Finally, the investigation outlined herewith plainly indicates that Mr. Hart's statements are in error. Possi- bly he has been led to extravagant claim by the wm thusiasm of advertising campaign, a not uncommon ocairrence in business. Jo APPENDIX I The following is a list of the books, articles and papers covering work on concrete from whieh much valuable information was obtained in the preyaration of this thesis. Le 4e 5. Ge Conerete Engineers Handbook, Hool and Johnson. Effect of Hydrated Lime on Portland-Cement Mortars, Henry 8S. Spackman, e The Effect of Hydrated Lime on Portland-Cement Mortars. Professor Harry Gardner. Letter - Portland Cement Association. J, B, Freeman. Letter = Hational Lime Association. ¥, He Harte Letter «- Jewis Institute, Professor Duff A. Abrams. APPENDIX ITe The following is a copy of the pian for the work on this thesis submitted previous to the beginning of the worke Subject: The effeot of hydrated lime on the tensile and compressive strength of mortar. Proportions: Neat, 2:1 and 3:1 Percentages (by weight) of lim: 0 = 5 - 10 - 18 2 = 25 oe 30. Age: 7, 14 and 28 days. Humber: 21 kinds x 3 different ages x 4 for each test = 252 briquets. Humber of eubes: The same as for briquets ~- 262. MICHIGAN STATE UNIV. LIBRARIES UNUM MTOM 312930087 12915 Cy