E'NCRE ASING THE TfiNSiLE WEE; NFTH OF CnN-CRETE BY USE OF ADMXTURES U1 Taosis fer i336 D:3'*~aa oi‘ M.- i';iC:al EGAN ST :63 30:1de {:3 Lemma A. Mi? f‘i‘; igéfi [7d - 11—15519; ”AIM." ‘31:?! t P. 0'? ‘ ".: . at?! J'HC‘"‘ "\ .H . llyi§ «l ‘h 'fi {El-1.. '4 -l‘ip‘{'i';'I‘ "a?” 1:? (L1,). ‘ fl! 1" M]??? £7. 'l. ‘ 49L):'.4: $r‘ 'élr'?‘ (‘ $9" "‘ J ' ‘fl? 7‘4," r w" ,. "fr "’17.":f'v'74 I, {f 't L: I A a" ' . “ l ' ' ‘ I" ’ "’ '1"; r .-" i a, ' ' ‘I \ 'l' I” '. 's -‘ ‘ ' ' I ‘ ' A . “ J"- < l_l'. ' ll ‘ .I l, r . '_ ‘. .l m‘ w " . ' {A -S‘ . I“ "'\ '. 'I “ ll ; i ‘ . I. ‘v ' .’_ f .p. - ‘ I t I . - 4 ll 1 ' ‘ r I l j " ' V . I This is to certifg that the thesis entitled Increasing the fensile otrength or Loncrete 1 by Use of Aomixtures 1 presented In] Leonard A. Robert has been accepted towards fulfillment ‘ of the requirements for _% 43‘.*_,degree inQiYiL,- _ ' Engineering Major professor l I l M—796 '. L___-_- -- - -4 ____ \ ‘ ‘ ‘ l ' ‘4 0 1 ‘ I ./ ‘ ’ ' 12".; “ _‘ .fl .‘3' 'A . , . ‘ ".l INORIABIIG 13: 2313153 scanners or ' column or as: or mum 3! new A. £03m A 233818 hunt“ to the Man a: Graduate studio. or lichisan State College or.A5riou1turo and Applied Science 1n.purt1|1 fulfill-out or the roguironcnta for the dosroc of WI! 0? 801E133 I] CIVIL ENGINEEIBG MARTINI OP CIVIL ENGINEERING 1946 7/Zce/L/L. ”MOVEMENT Acknowledgment is made to Professor 6. 1.. Allen and Professor 0. B. Andrews of the Department of Civil Engineering, Professor 0. D. Deiitt of the Department of Chemical Engineering and Dr. Thurs: of the lichim State mat-Is: Department for assistance and advice in developing the problem. L. A. R. 3 6.232,. 2r _'JI'UIJ¢._L.‘\ PUHP 083 1'0 find an admixture for portlend cement that will economically increase the tensile strength of the cement paste sufficiently to eliminate cracking in ordinary structures. IIDII Subject PART I Brief History of Portland Cement. Cheaieal Analysis of Portland Cement as known today. Some Admixturee tried by Others and Results in Brief. conclusions Derived from Readings. Iabulation of Results of Others of Significance. to this Ehesis. tables I to XVI. PM 11 Preface to thesis Imperiment. Experiment Procedure. table of lines and Procedures used. fabulation of Results - Tables I to XVII. Discussion of hperiment. Conclusion. Recon-endations . Bibliography. Graphs of Test Results - Samples 2 to 28. and 36 to 49, inclusive. Graph of Electrical Resistance - Ohms of Resistance offered by Cement Paste. Page dumb-J 12 ‘68 4o 57 61 62 53 65 106 BRIEF HISTORY Egyptian massive masonry is the first record of present day methods of bonding stone with mortar. The cementing material was gypsum (burnt). lime was not used in Egypt until the advent of the Roman.period. The gypsum was quarried in an impure state and poorly burned so that it set unevenly and, not being totally decomposed, would give the impression that line was used. Lime was more abundant but required more fuel, and fuel was scarce. It is probable that the use of lime as a mortar came from Persia to Greece, thence to Rome. the mortar was prepared by slaking lime and mixing with sand (modern practice). The Romans had the art sell perfected, but with the fall of the Roman empire all of this was lost. Medieval mortars were very poor. In 1765 Lariat, engineer on.the waterworks at Versailles, added quicklime to the mortar to obtain ins creased strength and impemmeability. DeLafaye contested this and recommended that egg-sized lumps of line should be immersed in water, transferred after a time to a cash and there allowed to slake. Ancient writers state that lime had to be slated for’years before using. Randelet discovered that it was not the method of slaking the u... but the thoroughness of mixing and ramming the mortar that 'made the Romanuwork excel. Chemical analysis, texture, and Indian practices confirm this. The tamping was so thorough that even today the interior mortar is not set. Greeks and Romans used a volcanic ash, finely ground and mixed with lime and sand, to make a mortar that was superior in strengthfland would resist water. Santorin earth in Greece, Pozsolana in Rome, and Trees in Russia and Germany are of this source. The Romans created arti- ficial Possolana by grinding up tile. the middle ages lost the art of burning lime and the knowledge of artificial or natural Possolana, Tress or Santeria earth. In avid cues are the very poor buildings of the ninth, tenth and eleventh centuries. Beginning with the twalfth century we not ice a gradual improvement in quality so that by the beginning of the fifteenth century excellent mortar is again in evidence. The father of modern cement is John Smeaton. His investigations led to the use of ”blue lies hydraulic lime" and possolana (1756). The forerunner of "portland cement" is credited to D. J. Yieat. Be prepared an artificial hydraulic line by calcining an intimate mixture of limestone and clay, ground together in a wet mill. Imy such attempts were being made during this period, the object being to dupli- cate what nature had done in creating a natural cement material in the- volcanic ash. Natural cements; i.e., Tress, Possalana, are materials formed by calcining a naturally occuring mixture of calcareous and argillaceous substances at a temperature below that at which sintering takes place. Vicat, Irony, linkler, Michaelis and Is Chatelier all contributed to the physical and chemical analysis of portland cement, but systematic work on portland cement was begun in the United States in the Geophysical Laboratory of the Carnegie Institute at Washington, D. C. in 1906. Since 1926 the P. C. A. has done much to im- prove cement. 7 Concrete is described by Vitruyius and is found in the vaults of the thermae and Basilica of Constantine; its use is at least that old. The‘Pantheon has concrete walls twenty feet thick. The Roman concrete was far superior to medieval concrete and was not equalled until the construction of the test India docks in 1800. Chemical Analysis as Known foday fhe chemicals in today's portland cement are Cao, CaOH,.HgO, 3102, A120; and PeO. The compounds formed by the addition of water and letting set are: sow-8102, mac-$102, 30131041203, SCaO-ZSiOQ, SOaO-3A1303, CaO-A1203, SCaO-511203, ZCaO-A1203-Sioz, 20aO-Pe203, CaO-Pego3, 4CaO-A1203-Pe203. Iricalcium silicate (30a0-8102) has all the essential properties of portland cement. It has initial and final set within a few hours after gauging and shows no un- soundness. Gypsum affects time of setting. Disaloium silicate (ZCaO-SiOQ) has no definite setting time and sets only slowly over a period of days and months. Gypsum does not affect time of setting. Tricalcium Aluminate (Bow-A1203) gives a flash set. The remaining compounds have been considered as negligible. Table I shows a strength analysis of the three major compounds. The relation of the strength of cements to their composition has been a rather intractable problem and the factors determining strength apparently are so numer- ous that any solution has seemed far off. The increase in our knowledge of the constitution of cement and of the compounds present in.it has, however, in recent times paved the way for some interesting work on this problem. The calculation of the contents of the various compounds in cement, erroneous to some extent as the values ob- tained may be, provides a preliminary basis for the allocation of strength. The compound contents, however, are far from providing all the data required for they purpose, because the strength of a cement is dependent also on the fineness to which it is ground and to some ex- tent on the amount of gypsum added; it may perhaps be influenced to some degree by some effects, at present unknown, of minor components such as the alkalis. Tests show that the strength of any mixture at any time might compare favorably with a ratio of the strengths of the separate parts as established in Table I. There are an insufficient number of tests to prove this; the only thing we know is that tricslcium silicate is mainly responsible for strength development up to twentyeeight days and that dicalcium silicate makes increasing contributions from twenty-eight days on. See Table 111. Reference 1, 19, 2. Portlmd cement on contact with water produces hydrated compounds in solution which, owing to their insoluble nature, become highly supersaturated. The decomposing and dissolving influence of the water upon the cement going on for some time reaches a point at which the supersaturated solution surrounding the cement coagulates. The gel layer forms about the cement grains and makes it more difficult for the grains to become hydrated, dicalcium silicate taking years, tricalcium silicate a few weeks and tricalcium aluminate a very short time. The gel is apparently a silica gel which in its final geological process would be flint of agate. It seems that if a method of stepping up this process could be obtained then we would get a better concrete. The gel is apparently amorphous. Tests made by Grun in which he reground cement which had set three days, and then reset three days, regrcund and reset again, show that in three days apparently only sixty-seven percent of the cement hydrated. See Table VII. Although, as previously stated, gypsum probably affects the strength of cement to some extent, from the information available it is safe to say that gypsum has no effect on the ultimate strength. Admixtures Tried and Results Celite. Celite has no effect on the modulus or strength of concrete up to twenty-eight days. Reference 14. Vegetable Oils. Vegetable oils are destructive. Reference 15. A1. or Fe. Together or separately will in- crease strength. Reference 20. Water glass. Harmful efflorescent action on concrete. Reference 24. Sodium chloride. Increased the tensile strength of cement. The difference is decidedly significant. Reference 25. Tricosol. One percent triccsol will allow ten percent reduction in water, will increase compressive strength eighteen psrcent and tensile strength forty- three percent. Reference 17. Gypsum, Sucrose, Calcium Chloride, Tannic Acid Triethanolamine, Ca (Ac0)2 323135. The detri- mental effects offset the good. Reference 30. Zinc Phosphate. Reference 27. Common salt. Improved the tensile strength of mortars. Reference 25. Tests with commercial and non-commercial admixtures in percentages ranging from two to fifteen percent of the cement. Indicate that slightly hydraulic admixtures showed only small increase in strength and nonshydraulic admixtures showed reduction in.strength up to about five percent fer each one percent of admix- ture in terms of weight of cement. Colloidal clays and diatomaceous earth gave greatest reductions in strength and, in general, reduction was greater at one to three days than at greater ages. Reference 21. The addition of arsenious oxide (As203). A thirty percent admixture gave forty percent increase in com- pressive strength at seven days and ninety days. The mixture has to be made at 520 to 374 degrees 1. Refer- ence 18. Electric Heating of Concrete. This interesting article describes the experiments and experiences gained from the use of electric heating of concrete for cold weather construction. Reference 3. From the literature available we conclude: 1. That fineness of grinding and the combined lime and silica present determine the aged strength. 2. A raised early strength and lowered late strength of mixtures may be the result of alumina con- taining compounds mixed with the calcium sili- cates in the absence of a retarder. The addition of tricalcium aluminate causing a reduction in 3. 4. the water available to the tricalcium silicate may be responsible for the increase in early strength. The development of tricalcium aluminate hydrate paste may influence a lowered late strength. The influence of the alumina containing compounds is attributed to the rapid development of a weak and open structure by the crystalline tricalcium aluminate hydrate; thus preventing optimum contacts of the hy- drating calcium silicate grains. The distribution of the water is as essential a factor as the total amount of water in com- bination. The structure and nature of the hydration.of the colloidal calcium silicate hydrate appear to establish the rate of develop- ment of compressive strength, and not by hy- drolysis or by the total fixed water of hy- dration. Tricalcium aluminate hydrate, a fluffy crys- talline isotropic hydrated calcium aluminate, is formed rapidly when alumina compounds are treated with water. The compounds chiefly responsible for high compressive strength in portland cement are tricalcium silicate and beta-dicalcium silicate, gauged with water to make a paste. Triealcium silicate reacts with water rapidly, both by hydrolysis and hydration; beta-dical- cium silicate remains practically unhydralysed but combines with water to form fixed water of hydration, very slowly during the first month, but approaching the hydration value attained by tricalcium silicate in a year. Crystalline calcium hydroxide and amorphous hydrated calcium silicate, of composition approaching the beta-dicalcium silicate hy- drates to approximately the same amorphous hydrated silicate, are products of the reaction of water on tricalcium silicate. Traces of crystalline calcium hydroxide have been observed. crystalline tricalcium aluminate hydrate and an amorphous hydrate ‘the composition of which has not been definitely established) are pro- ducts of the reaction of quadra calcium alumi- nate ferret; and water. The quadrafaluminate ferrate and the dicaleium ferrate, mixed with the calcium silicates in the absence of a retarder, lower the compressive strength of the mixtures. it is suggested that this may be due in part to the precipi- tation upon the grains of the hydrating calcium silicates of amorphous calcium ferrate hydrate, thus retarding the rate of impenetration of the water and reducing the bonding action. 10. 11. 13. 10 The initial set is retarded by the use of gypsum. Gypsum reacts with the alumina that enters into so lution with the formation of crystalline calcium sulphoaluminate; this occasions a delay in the development of the crystalline hydrated tricalcium aluminate. Gypsum tends to counteract the influence of the alumina in lowering the compressive strengths of the calcium silicates. It is suggested that this favorable influence may be associated with a retardation in the development of the tricalcium aluminate hydrate due to effects of the prior formation of calcium sulfoaluminate permitting the structure of the set paste to be established by the hydrating tricalcium silica e. Gypsum also tends to counteract the influence of the ferric-oxide containing compounds in lowering the compressive strengths of the calcium silicates. It is suggested that this favorable influence may be associated with the formation not only of calcium sulfoaluminate, as above, but also of the calcium sulfoferrite and the consequent reduction in the amount of the amorphous ferrite hydrate that can be de- posited on the grains of the calcium silicates. Dicalcium silicate produces nothing but gel; 14. 15. 16. 17. 11 so even if it had early strength it would be of no value. All-purpose cement cannot be.made from any one compound. The compounds have an optimum proportion.one to another. Amorphous silicate, upon crystallization, becomes agate quarts ($102 hardness 7, specific gravity 2.65 and crystalline) or Calcite (Coco; hardness 3, specific gravity 2.70 and crystalline) (limestone or marble) . Control in time of setting is facilitated by increasing silica and decreasing alumina. Delayed development of full strength.may be obtained by increasing silica at expense of lime. Steam.curing does not develop any strength but develops the strength in a shorter time. References: l,2,5,7,8,9,10, 11,15,26. 1131:] I EESI-LE 81333313th cm COIEOUNQS STORED II [ATE W slum 1 ‘L as ._.21.___l§a_._2_26 (1) 20.0 8102 - - 98 558 616 no (2) 50.0 no 440 693 712 683 657 642 (5) acao 11253 100 155 125 - - - 811(1) 191(5) 98 105 192 576 sec 614 311(2 191(5 267 665 see 562 551 so: 591(2 501(1 166 562 527 610 576 77s 4o.51(1) 40. 51(2) 307 452 671 681 671 so: 191( (5) h: IQTAR W . - I W (1) 20.0 3102 - ' 25 194 225 (2) 50.0 sic6 270 4c? 571 «- (3’ 30‘6 A12 3 . " - 4‘ 811(1)191(5) 4o 58 260 as: e11(2) 191(5) 550 595 556 - 501( (250) 501(1) 119 220 520 «- 40.5$(1) 4051(2) 191(3) 198 247 335 - Data after Bates 31 Plaster of 93) added except Paris (1.651 8 12 13 TABLE II swam-Ins In 1 ,3 saunas wuss 310m __ _ 1 A ._ W 3Ca0 I102 114 199 . 2 3060 3102 (51 mm) 156 199 515 751 3060 3102 251 503011203 214 284 455 30a0 A120 - e 43 601 SCaO 3102 20$ 30a0 11203 20% gypsum 214 - 270 Bates TABLE III muons 701 50:0 3102 101 20.0 8102 501 50:0 0102 501 20:30 3102 _ new 5000 6000 6000 6000 1200 2000 5000 6200 14 WW WQQGUI#UMH CONCRETE GOIPRESSIVB 940 950 1180 750 1530 530 855 625 870 2330 3420 2220 2700 3720 1960 2630 2700 3250 3300 4580 3020 4400 4790 3480 3780 4450 4690 4650 5230 4520 5350 5390 5500 4770 5550 5580 TABLE IV 5750 6840 5760 6160 6000 6070 6490 5830 5870 1:5 mortar water cured (both) 519 570 415 501 455 549 551 425 424 HORTAR IENSIII 492 525 494 523 552 501 473 512 563 579 610 530 631 628 607 527 526 604 644 666 644 615 626 632 610. 388 668 15 13234 mix,‘water cured and water cement ratio .60(wt.) TABLE V. MW 03.1.e203._§102.2mz_11_20 .12er 1 65.6 .30 5.48 2.79 21.42 0.45 0.36 0.61 2.49 2 62.1 1.12 5.69 3.99 21.18 0.29 0.12 0.77 3.10 3 61.3 2.32 7.32 3.50 19.45 0.38 0.27 1.03 4.00 4 63.8 3.27 6.49 2.74 18.15 0.36 0.23 0.55 2.49 5 66.1 0.92 5.16 2.36 19.69 0.38 0.38 0.40 3.11 6 64.7 2.72 4.93 3.33 19.52 0.29 0.37 0.85 2.21 7 65.4 0.87 5.42 3.07 20.64 0.27 0.59 0.39 2.05 8 66.9 0.65 6.28 2.90 19.38 0.39 0.22 0.79 1.89 9 66.3 0.86 4.80 2.42 20.78 0.29 0.60 0.42 2.48 TABLE VI mmwmmmmm2mumznm l 1.3 9 10 51 23 75 2 .5 12 8 56 11 77 3 1.1 11 14 31 33 69 4 2.0 8 13 55 12 79 5 3.7 7 10 57 13 83 6 1.9 10 7 63 9 55 7 3.5 9 9 48 2 75 8 2.9 9 12 62 9 69 9 1.7 7 9 62 13 77 lie...d:i mmqehunau NH TABLE VII ,3. __Q _1D _:3 A I 2.76 2.96 2.64 3.05 5.01 5.02 2.00 5.04 2.95 0.94 1.00 0.90 1.04 1.01 1.01 0.98 1.04 1.01 0.94 1.00 0.90 1.03 1.02 1.02 0.98 1.03 0.99 0.92 0.99 0.88 1.00 0.98 0.98 0.92 0.99 0.96 0.91 0.98 0.86 1.00 0.99 0.99 0.94 1.00 0.96 1.03 1.07 0.96 1.11 1.10 1.10 1.06 1.12 1.09 0.95 1.02 0.95 1.12 1.07 1.07 0.99 1.05 1.01 2.59 1.88 1.80 1.97 2.36 2.36 2.43 2.11 2.88 0801/ (3102 A1203) Ca0‘/ (2.83102 1.1011203 0.7020203) 060 / (2.003102 1.1011203 0.6556203) (CaS-Iree CaO) / (2.88i02 1.1811203 0.0 / (2.0 3102 1.65A1203 .5556203) 080 / (2.550102 1.65A1203 1.0526203) (060 1.4!00) / (2.00102 1.111203 0.726203) 0102 / (11203 1.203) 41203 / re2°} ___§._...fl..__;l_. 1.96 1.42 2.09 2.37 1.48 1.48 1.76 2.16 1.98 18 3 days 7 days 28 days TABLE VIII 5170 940 256 5940 1510 555 6000 1050 655 Grun l9 TABLE IX 1;} SAsu.IQRTAh3 AT 7 DAYS WATER CEMENT NATIO Percent Tensile strength m 1 1.1191631124121111. 8 410 9 400 10 340 11 280 12 230 20 TABLE 1 1:3 SAID MOH'l‘ARS WAT“ UEMEN’I‘ RATIO UOIPKESSIVE STRENGTH __..._!Az 11-“ 1211- - 1:1 00.. 28.01....“ 0.52 725 1114 1407 0.56 777 1250 1866 0.60 1055 1484 2292 0.64 10840 1640 2595* 0.68 1040 1682s 2510 o . 72 784 1615 2290 0.76 760 1425 2170 iv inconsistent TABLE LI MIMI 01" CURING - 1 _1_ 1111_ A __gkm*_gw-3d§, flds «hrgyids. Test 1 air cured 345 water cured 324 Test 2 air cured 458 water cured 501 454 520 517 607 lyr 419 562 671 554 632 623 161*er 01' TWWTURE TABLE XII 11118122321 13:3. 3 ds. 7 <19. 28 ds_._ Normal cement 2 - 199 800 1916 ll - 564 1158 2248 17 373 925 1472 2625 25 493 1096 1586 2946 35 620 1349 1950 3036 High early 2 50 459 1961 3846 strength 11 225 1443 2469 3604 17 575 1951 2831 4076 25 1106 222]. 2865 4263 35 1686 2698 3004 4043 24 l'ABIE XIII STEAM CURING STEAM AT 100 DEGREES FOR 16 hOURS TEST 'l'hEIV WA‘i‘Jéid Al‘ 22 DEGREES Obi MOIST AIR AT 22 DEGREES No. Ids. 7 is. 28 d3. lfid§_.~_h_fl dqgwggddsg 1 195 200 200 75 345 470 2 300 305 355 75 290 465 3 215 210 220 200 500 520 4 160 170 185 . 55 255 ' 405 #3 was quick setting cement. TABLE XIV CONCRETE STORED IN MOIST AIR 24 80088 BEWORE STEAK IS APPLIED STEAILPRESSUHE 68 103 197 MOIST AIR TIME Or CURING 18hrs.42hrs.18hrs.42hrs.18hrs.42hrs.7ds.2863. #UMH 2660 3330 3550 3460 5480 5050 5470 5760 5350 5120 4760 5580 7140 5470 6670 7160 6970 6000 5730 6110 7600 5280 6340 7030 5480 6200 6790 2740 5080 6760 2560 5080 CEMENT Clinkered Melted TABLE 17 7 ds. 358 220 28 ds. 421 306 26 TABLE XVI 011111110111. PROPORTlOulnu Or PORTLAND onMENT wlTnlN LIMITS CEO 60 - 70 Fe 03 0.5 " 6 310 17 - 25 M 0.1 - 5.5 11283 5 - 8 N820 so 1 - 5 plus K20 0.5 - 1.5 3 27 28 PAH! II PREFACE The effect of chemical composition on the tensile strength or concrete has been quite thoroughly in- vestigated; however, most of it has been on the basis of chemical logic, and we find that many of our most important developments have been illogical in approach or purely accidental. An example of the latter is the discovery of what is marketed today as air-entraining cement. A few years ago highway men were very.much concerned over the fact that concrete highways were scaling off, except for a few highways in new York that had all been made of the same cement. Chemical analysis and the knowledge of'the plant chemist could not determine why that cement was different from any other; the processes were all alike. the story unravels as follows: In the process of grinding the clinker to the required fineness we make use of a ball mill which is loaded with about six ton of steel balls from two to five inches in diameter. these balls must be cleaned once each twelve hour shift, a very tedious Job. the men responsible for the equipment, being very human, were often discouraged with the difficult cleaning Job; so one night one of them, having a particularly difficult time, threw a couple of shovels 29 of coal into the mill, hOping it would clean up the balls; and it did. Thereafter he used this method of cleaning the equipment, being very careful not to let anyone see him do it. In due time his partner on the other shift was informed of the method and cautioned to keep quiet about it. The two later discovered that a little grease and one shovel of coal would do the job very well. When the chemist had exhausted all of the chemical analysis he knew he began to question the men in the plant to get their opinion. The ball mill operators did not break down immediately; but later, observing that the chemist was greatly disturbed, they gained his confidence and told him what they had been doing, voicing the opinion that perhaps this was the reason for the different property of that particular cement. The results of tests were positive, and air- entraining cements were on the market. We offer this story to appease any of the chemists who might think that in the work which follows we might have stepped out of bounds. 30 [11186, scrum, ovum. Ann TESTING momma; It was decided to test a few chemicals as admix- tures under the following conditions of setting and curing: ”A. Twelve specimens were made from the sample, placed in forms and left to set under the influence of electric, D. 'C., current for twenty-four hours. :The specimens were then placed in water; at seven, fourteen, twanty-one and twenty-eight day ages res- pectively, 3 specimens were removed, one tested immediately and two left in air to be tested at about one hundred and forty days. The exact age is given with the data on each sample. The average breaking stress of the two test specimens is recorded. RBI . Twelve specimens were made from the sample. All specimens were left in forms twmty-fcur hours and then placed in water. At seven, fourteen, turentyc-one and twenty-eight day ages respectively, three specimens were removed from the water, one tested immediately and twa left in air to be tested at about one hundred and forty days. The enact age is given with the data on each sample. The average breaking stress of the two test specimens is recorded. '0. Twelve specimens were made from the sample, placed in forms and left to set under the influence of 31 electrical, D. 0. current for twenty-four hours. Bight specimens were left in air until tested, one at seven, one at fourteen, one at twwiy-one, one'at twenty-eight and four at about one hundred and I seventy-five days. The average of the four breaking stresses is recorded. Four specimens were left in air seven, fourteen, twenty-one and twenty-eight days; then twwty-one, fourteen, seven and seven days in water respectively; then in air until tested at about one hundred and seventy-five days. The exact age is given with the data on the sample. I”. Twelve specimens were made from the sample. All specimens were 2b ft in forms twmty-four hours, then removed and placed in air. Eight specimens were left in air until tested, one at seven, one at fourteen, one at twenty-one, one at twenty-eight and four at about one hundred and seventy-five days. The exact age is given with the data on each sample. The average breaking stress of the four test specimens is recorded. Pour specimens were left in air seven, fom‘teen, twenty-one and twmty-eight days; then twenty-one, fourteen, seven and seven days in water respectively, then in air until tested at about one hundred and seventy-five days. The exact age is given with the data on the sample. 32 Test Ho. 1 Test number one was a control test to determine the current and voltage best suited for these parti- cular test specimens. It was found that a voltage of near forty with a current of three-tenths ampere was about right for the specimen. This volt-amperage value was small enough so that temperature rise was negligible, and the current was small enough not to cause excessive hydrolysis, but enough to effect a result. Test no. 2 2,860 grams of cement. 988 c.c. of tap water. Test procedure ”A” Test no. 3 Sale '13“ 2e Test procedure '5' Test no. 12 Same mix as 2. Test procedure 'A' Test lo. Test lo. Test no. Test no. Test 10. Test Ho. 13 2O 21 4 22 33 Same mix as 2. Test procedure "B” Same mix as 2. Test procedure '0' Same mix as 2. Test procedure ”D" 2,860 grams of cement. 988 c.c. of tap water. 34 grams of urea. Test procedure I'B" Same mix as 4. Test procedure 9A" Same mix as 4. Test procedure "D" Test lo. 5 Test no. 15 Test so. 23 Test no. 7 Test no. 9 Test lo. 25 54 2,860 grams of cement. 916.5 c.c. of water. 71.5 c.c. 40% solution formaldahyde Test procedure '3' Same mix as 5. Test procedure "A” Same mix as 5. Test procedure 'D” 2,860 grams of cement. 28.6 c.c. of phenol 959.4 c.c. of water Test procedure '3' Same mix as 7. Test procedure "A” Same mix as 7. Test procedure ”D" Test no. Test no. Test 10. Test no. Test no. Test no. 16 24 10 17 26 2,860 grams of cement. 17 grams of urea. 55.7 c.c. of formaldahyde (40$ sol.) 952.3 c.c. of water. Test procedure "B" Same mix as 8. Test procedure "A" Same mix as 8. Test procedure "D” 2,860 a of cement. .35. c.c. of formaldahyde (40$ sol.) 494 c.c. of carbolic sol. as in 7. 458 c.c. of water. Test procedure '3' Same mix as 10. Test procedure ”A" Same mix as 10. Test procedure '9' 35 Test no. Test so. Test so. Test lo. Test lo. Test Ho. 11 18 27 14 19 28 36 2,860 grams of cement. 14.3 c.c. of phenol. 17 grams of urea. 973.7 c.c. of water. Test procedure '3' Same mix as 11. Test procedure "A” Same mix as 11. Test procedure l'D" 2,860 grams of cement. 9.5 c.c. of phenol. 11.3 grams of urea. 23.8 c.c. of formaldehyde. 954.7 c.c. of water. Test procedure '3' Same mix as 14. Test procedure ”A" Same mix as 14. Test procedure "D" Test lo. 41 Test lb. 42 Test Ho. 36 Test no. 37 Test so. 38 37 953 grams of cement. 2,859 grams of sand (Ottawa 30-50). 582 c.c. of water. 9.5 grams of urea. Test procedure '3' 953 grams of cement. 2,859 grams of sand (Ottawa 30-50). 558 c.c. of water. 23.8 c.c. of formaldahyde. Test procedure '5“ 953 grams of cement. 2,859 grams of sand. 582.5 c.c. of water. Test procedure “5' Same mix as 36. Test procedure "UP 2,860 grams of cement. 988 c.c. of water. 85.8 grams of z. Test procedure ”A“ *— ' Test so. 39 Test 16. 40 Test we. 43 Test so. 49 Test no. 44 Test lo. 45 Same mix:as 38. Test procedure '3' Same.mix as 38. Test procedure 'D' 2,860 grams of cement. 28.6 grams of magnesium sulphate. 988 c.c. of water. Test procedure '5' Same mix as 43. Test procedure "D” 2,860 grams‘of cement dissolved in solution of i of 15 stearic acid solution in bensine; let dry and powder. 988 c.c. of water. Test procedure '3' 2,860 grams of cement. 28.6 grams of sodium cxylate. 988 c.c. of water. Test procedure '3' Test lo. 47 Test lo. 46 Test lo. 48 39 Same mix as 45. Test procedure "D" 953 grams of cement. 2,859 grams of sand (Ottawa 30-50) 588 c.c. of phenol solution (same concentration as used before). Test procedure '5' 2,860 grams of cement. 28.6 grams of silicate of soda. 988 c.c. of water. Test procedure '3' Test lo. 6 3 4 7 Chemical Admixture TABLE I SPECIMENS 24 hOURS In Pawns 6 DAYS II WATER Breaking Condition stress psi. of setting 1480 E1. 1430 P1. 1380 P1. 1300 P1. 1275 E1. 1250 P1. 1240 El. 1230 El. 1155 P1. 1110 P1. 1050 El. 1000 P1. 990 El. 912 P1. 878 P1. 863 P1. 850 P1. 795 P1. 753 ml. 734 P1. 660 El. 572 El. 433 P1. 424 P1- 169 P1. 69 Pl. " Ble " Ple nemenclature U urea Pl Plain C Phenol P Formaldahyde Spec. Special Z Phosphorus Pentoxide 8 Sand El Electric 40 Test lo. 6 l3 7 5 17 18 Chemical Admixture Pl TABLE II SPEUIMHBS 24 nOURS In FORKS 13 DAYS IN WATER Breaking Condition stress psi. of setting 1690 31. 1580 P1. 1495 P1. 1430 P1. 1355 El. 1360 El. 1350 P1. 1300 P1. 1285 El. 1270 P1. 1273 El. 1230 P1. 1285 El. 1125 P1. 1150 91, 1125 P1. 1125 P1. 1050 P1. 734 El. 840 P1. 527 P1. 130 P1. - Ele - Ele - Ple - Ple - El. - Pl. Nomenclature U urea P1 Plain C Phenol r Formaldahyde Spec. Special 2 Phosphorus Bentoxide 8 Sand El Electric 41 Test no. 6 45 13 15 45 la 9 12 10 s 5 4 4e 5 11 14 44 46 41 5e 7 17 2 16 19 42 38 39 Chemical Admixture U ngso, P1 I H90 U-C. 0 Pl F.C. U.F. 1““ 111 SPsulmssS 24 nouns in roams 20 quS is IATER Breaking Condition stress psi. of setting 1580 El. 1485 P1. 1450 P1 . 1440 El. 1440 P1. 1425 E1. 1400 El. 1410 El. 1230 P1.. 1210 P1. 1200 P1. 1200 P1. 1140 P1. 1120 P1. 1115 P1. 1100 P1. 870 P1. 650 P1. 540 P1. 178 P1. - P1 e - El. - 31. " E1 e " B]- e - P1. - El. - P1. Nomenclature U Urea P1 Plain C Phenol r Pcrmaldahyde Spec. Special 3 Phosphorus Pentoxide S Sand El Electric 42 Test Ho. 3 2 18 10 17 4 11 Chemical Admixture P1. P1. U.O. F.C. POO. U U.C. C.U.P. I '0 P1. U.P. 3 C.U.P. 0 P1. H802 I83102 P 13304 0.3. Spec. C 3.0. SOP. SeUO Z 2 TABLE IV SPECIMENS 24 80083 IN POEMS 27 BATS In VATER Breaking Condition stress psi. of setting 1710 P1. 1640 El. 1445 El. 1360 P1. 1275 El. 1250 P1. 1223 P1. 1125 El. 1050 P1. 920 El. 800 El. 790 ‘P1. 760 P1. 536 P1. 400 P1. 351 P1. . Ple ‘ Ple " El. " Ple - Ele "' Ple " El. ’ Ple " Ple "’ Ple " El. “ Ple lbmenclature U Urea Pl Plain C Phenol P Formaldehyde Spec. Special z Phosphorus Pentoxide S Sand El Electric 45 TABLE V SPECIMENS 24 HOUKS In FORMS 6 DAYS IN LLB. AIR Test Chemical Breaki ng Condition llo. Admixture stress psi . of setting 20 P1 553 E1 . 2 6 P . C . 502 P1 . 24 UJ'. 482 P1 . 23 1’ 472 P1. 27 U. C . 464 P1 . 47 H80 427 P1 . 2 5 o 389 P1 . 21 Pl 371 P1 . 37 s 338 P1 . 28 C .11.! . 320 P1 . 22 U 317 P1 . 40 Z - Pl . Nomenclature U Urea P1 Plain C Phenol 1' Formaldehyde Spe c . Special 2 Phosphorus Pentoxide 8 Sand El Electric Test no. 49 2O 22 21 27 25 26 47 23 24 37 28 40 Chemical Admixture MgSO4 Pl U Pl U.C. C 1.0. NaO P U.P. 3. 0.0.1. 2 TABLE VI SPEJIMENS 24 801.183 IN £01113 13 DAIS In LAB. AIR. Breaking Condition stress psi. of setting 750 P1. 750 El. 748 P1. 657 P1. 603 P1. 550 P1. 373 P1. 380 P1. 376 P1. 319 P1. 315 P1. - Ple . Ple Nomenclature U Urea Pl Plain C Phenol P Formaldehyde Spec. Special 2 ‘Phosphorus Pentoxide Sand Electric 45 Test no. Chemical Admixture U.C. P1 C nao 1.0. P1 U.P F , TABLE VII Breaking stress psi. 1115 790 755 750 712 652 562 550 520 277 180 Nomenclature U P1 C I Spec. 2 3 El urea Plain Phenol Formaldehyde Special SPEULMENS 24 hOURS IN FORKS 20 DAYS Is LAB. AIR Condition of setting Pl. E1. P1. P1. P1. P1. P1. P1. P1. P1. P1. P1. P1. Phosphorus Pentoxide Sand Electric 46 TABLE VIII SPECIMENS 24 BOUKS IN FORMS 26 DAYS In LAB. AIR Test Chemical Breaking Condition lo. Admixture stress psi. of setting 27 ‘U.C. 1375 P1. 22 U 1275 P1. 21 P1 1050 P1. 25 C 1030 P1. 26 3.0. 1030 P1. 24 U.P. 440 P1. 23 P 350 P1. 37 S 320 P1. 20 P1 " El. 28 0 one P. "" P]. e 49 US$04 ' P1- 47 H30 ' Ple 40 Z " Ple nomenclature U Urea Pl Plain C Phenol P Permaldahyde Spec. Special 8 Phosphorus Pentoxide S Sand E1 Electric TABLE II SPECIMEHS 24 BOUHS IN FORKS 6 DAYS IN WATER THEN IN LAB. AIR UNTIL TESTED A‘i‘ AGE SHOWN Test Chemical Age Breaking Condition no. Admixture days stress psi. of setting 12 P1 129 870 E1. 48 la8102 175 818 P1. 42 3.1. 175 795 In” 14 0.0.1. 149 775 P1. 36 S 175 750 P1. 11 0.0. 129 720 P1. 7 C 115 715 P1. 44 Spec 175 690 P1. .41 3.0. 175 680 P1. 6 U 115 650 El. 19 0.0.1. 175 635 El. 46 8.0. 175 595 P1. 18 0.0. 146 575 in. 10 1. 0. 120 550 P1. 13 Pl 129 540 P1. 3 P1 116 540 P1. 15 1 148 540 El. 2 P1 116 475 El. 5 1 116 460 P1. 9 C 120 440 so. 16 0.1. 147 400 El. 17 ‘0.1. 147 385 E1. 43 mm; 175 380 P1. 38 z 175 390 E1. 4 U 116 380 P1. 45 sec 175 370 P1. 8 0.1. 121 370 P1. 39 Z 175 - P1. lemenclature U urea P1 Plain C Phenol 1 Formaldahyde Spec. Special z Phosphorus Pentoxide 8 Sand E1 Electric TABLE I SPECIHEHS 24 BOUHS IN FORMS 13 DAYS I! HATE THEN IN LAB. AIR UNTIL TESTED A‘i‘ AGE 3110']. Test Chemical Age Breaking Condition lo . Admi xture days stress psi . of setting 48 NaSiOz 175 976 P1 . 13 P1 129 860 P1 . 42 S. 1. 175 855 P1 . 36 S 175 815 P1 . 41 S .U. 175 760 P1 . 46 S . 0 . 175 720 Pl . 2 Pl 116 600 El . 12 P1 129 600 El . 14 0.0.1. 149 550 P1. 16 0.1. 147 545 11 . 11 0.0 . 129 520 Pl. 15 1 148 520 El . 5 1 116 490 P1 . 8 0.1. 121 470 11 . 45 laO 175 430 , Pl . 9 0 120 470 El . 10 1.0 . 120 410 Pl . 3 P1 116 390 Pl . 18 0.0 . 146 375 El . l9 0 .U. 1. 17 5 360 E1 . 7 0 115 355 Pl . 4 0 116 320 Pl . 6 U 115 280 El . 38 z 175 280 El . 17 1 . C . 147 275 11 . 43 lgSO4 17 5 185 Pl . Nomenclature U Urea P1 Plain 0 Phenol 1 Pomaldahvde Spec. Special 2 Phosphorus Pentoxide 3 Sand E1 Electric TABLE II SPECIMBNS 24 BOURS IE EQRMS 20 DAYS IN WATER THEN I! LAB. AIH UNTIL TESTED AT AGE SHONE. Test Chemical Age Breaking Condition 10. Admixture days stress psi. of setting 12 Pl 129 920 El. 3 Pl 116 870 P1. 42 3.1. 175 860 P1. 13 Pl 129 760 P1. 41 8.0. 175 760 P1. 36 S 175 725 P1. 46 8.0. 175 705 P1. 48 NaSiOz 175 690 P1. 44 Spec 175 637 P1. 15 1 148 578 El. 6 ‘0 115 570 E1. 14 0.0.1. 149 470 P1 . 7 C 115 455 P1 . 9 0 120 440 E1. 10 1.0. 120 440 Pl. 11 0.0. 129 410 P1 . 18 ‘0.0. 146 400 31. 2 P1 116 400 In. 16 0.1. 147 390 11. 45 sec 175 360 Pl. 5 1 116 330 P1. 4 U 116 310 P1. 8 0.1. 121 270 Pl. 43 0330 175 260 Ian 19 0.0.1. 175 240 11. 38 z 175 230 El . 17 1.0. 147 210 El. ldmenclature 0’ Urea Pl Plain C Phenol 1 Formaldehyde Spec. Special 2 Phosphorus Pentoxide S Sand El .Electric TABLE III SPECIMEN 24 800113 IN 108118 27 DAXS In WATB THEN In LAB. Ala UNTIL TESTED AT ACE Snows. Test Chemical Age Breaking Condition 1o. Admixture days stress psi. of setting 44 Spec 175 1000 P1. 42 3.1. 175 880 P1. 46 8.0. 175 815 P1. 36 S 175 775 P1. 3 P1 116 740 P1. 41 8.0. 175 715 Pl. 18 0.0. 146 545 El. 15 1 148 530 Ba. 19 0.0.1. 175 530 El. 12 P1. 129 520 E1. 9 0 120 470 El. 45 laO 175 460 Pl. 13 P1 129 430 P1. 5 1 116 410 P1. 16 0.1. 147 410 11. 38 z 175 410 El. 14 0.0.1. 149 380 P1. 7 C . 115 360 P1. 10 1.0. 120 350 P1. 2 P1 116 344 El. 4 U 116 330 P1. 11 0.0. 129 320 ‘P1. 45 I580, 175 505 P1. 8 0.1. 121 - 260 Pl. 17 1.0. 147 260 El. 6 U 115 250 El. Nomenclature U Urea Pl Plain C Phenol 1 Formaldehyde Spec. Special z Phosphorus Pentoxide 8 Sand El Electric TABLE XIII SPECIENS 24 BOUKS IN FORMS, 6 HAYS IN LAB. AIR, 21 DAYS IN WATER; THEN IN LAB. AIR UNTIL TESTED AT AGE 3110". Test Chemical Age Breaking Condition lo . Admixture days stress psi . of setting 21 P1 175 765 P1 . 37 8 175 750 11 . 26 1.0 . 175 590 P1 . 49 IgSO 175 575 Pl . as 0.0.3. 175 570 Pl. 27 U. 0 . 175 450 Pl . 47 laO 175 430 Pl . 24 0. 1. 175 373 P1 . 2 5 0 147 190 P1 . 20 Pl 175 180 El . 22 U 175 177 Pl . 23 1 175 - Pl . 40 s 175 - Pl . Nomenclature U Urea Pl Plain 0 Phenol 1 Pox-maldahyde S}: c . Special 7. Phosphorus Pentoxide S Sand 11 Electric TABLE XIV snows 24 1100118 In rows, 13 nus In 1.1». All! 14 ous IN wuss; TnEs In no. 1m UNTIL new» AT lea new... Test Chemical Age Breaking Condition Io. Admixture days stress psi. of setting 21 P1 175 890 P1. 23 1 175 870 P1. 49 03304 175 708 P1. 37 S 175 610 P1. 47 lac . 175 590 Pl. 22 U 175 390 Pl. 24 0.1. 175 373 4P1. 28 CeUe’e 175 37° Ple 27 0.0. 175 275 Pl. 26 1.0. 175 270 P1. 20 P1 175 270 11. 25 0 147 210 Pl. 40 z 175 - Pl. Homenolature ‘U Urea P1 Plain 0 Phenol 1 Formaldehyde Spec. Special Z Phosphorus Pentoxide 8 Sand El Electric TABLE XV SPECIMEAS 24 BOUHS In roams, 20 ours IN LAB. AIR 7 BAXS In wuss; Tum Is Ins. AIR UNTIL TESTED A‘i‘ AGE SBOWN. Test Chemical Age Breaking Condition lo. Admixture days stress psi. of setting 24 0.1. 175 970 Pl. 49 Hg304 175 858 ‘11. 37 S 175 530 Pl. 27 0.0. 175 530 P1. 26 1.0. 175 520 P1. 47 use 175 480 P1. 22 p U 175 450 P1. 21 P1 175 410 P1. 23 1 175 355 P1. 20 P1 175 300 El. 25 0 147 270 .P1. 28 0.0}1. 175 180 Pl. 40 Z 175 - Ple Homenclature 0' Urea P1 Plain 0 Phenol 1 Permaldahyde Spec. Special 3 Phosphorus Pentoxide 8 Sand E1 Electric TABLE XVI SPwIIENS 24 nouns In rows, 27 ous In m. 111:, 7 mus In WATER; THEN 10 1A8. AIR UNTIL TESTED AT ACE snows. Test Chemical Age Breaking Condition no. Admixture days stress psi. of setting 21 Pl 175 1660 P1. 23 1 175 1180 Pl. 24 0.1. 175 1070 ‘P1. 27 0.0. 175 940 P1. 26 1.0. 175 820 Pl. 47 EaO 175 620 P1. 49 lgSO 175 610 P1. 28 0.0. . 175 590 Pl. 22 U 175 560 P1. 37 8 175 550 Pl. 20 Pl 175 390 El. 25 C 147 370 Pl. BOmenclature 0 Urea P1 ‘Plain C Phenol 1 1orma1dahyde Spec. Special Z Phosphorus Pentoxide 3 Sand E1 Electric TABLE XVII SPECIIBNS 24 BOUhS Is rOmMS Tune In LAB. Ala usTIL TESTED AT ACE SHOWN Test Chemical Age Breaking Condition 10. Admixture days Stress psi. of setting 27 0.0. 175 1260 1125 1200 1030 1155 Pl. 21 P1 175 1000 720 1160 940 960 P1. 26 1.0. 175 760 820 1100 870 890 P1.\ 28 0.0.1. 175 610 - - 1100 855 P1. 25 0 147 520 950 1080 860 850 P1. 22 U 175 640 930 1030 810 850 P1. 49 lgSO4 175 956 646 770 770 785 P1. 23 1 175 340 710 1025 690 690 P1. 24 0.1. 175 870 1040 - 630 635 11. 20 P1 175 660 530 640 680 630 El. 47 sec 175 660 690 530 620 625 Pl. 37 8 175 400 440 410 350 400 P1. 40 z 175 - - . - - Pl. Nomenclature ‘U Urea Pl Plain C Phenol 1 Formaldehyde Spec. Special Z Phosphorus Pentoxide S Sand E1 Electric 57 DISCUSSIOA The tests were, in the most part, made with neat cement. The improvement of the cement being attained, a study of the concrete with the improved cement would follow. The criticism of such a procedure is that it is not standard and that it gives irrational results. I concede that.the results are not too good to compare with results obtained by others, but as it was not my objective to compare results with those of others, but to compare the results of various mixes and procedures as made by myself, I am satisfied that the results are sufficiently consistent to form an Opinion. Let no point out that although the standard tests on concrete and mortars make use of a test specimen that has been cured in water for the full period of aging, in the construction of buildings we seldom cure our concrete over three days. It has been my objective here to try to duplicate to some degree what happens in the field and to find out if under these conditions certain admixtures would increase the strength of my cement paste. A study of the results shows that after seven days (one day in forms, six days in.water) urea, phenol, formaldehyde, sodium oxide and sodium silicate did not lower the strength of the cement paste; that after fourteen days (one day in forms, thirteen days in water) 58 urea, formaldehyde and phenol, by themselves and in combination, show an average better than plain cement while sodium oxide, magnesium sulphate and sodium silicate are on a par with plain cement; that after twenty-one days (one day in forms, thirteen days in water) urea, formaldehyde, phenol, magnesium sulphate and sodium silicate and combinations of urea, phenol and formaldehyde are still on a par with plain cement; that after twenty-eight days (one day in forms, twenty- six days in.water) urea, formaldehyde, phenol and com- binations thereof are still holding their own with plain cement. Looking now at the specimens that were with- drawn frcm the water and placed in laboratory air at periods of time parallel to above stated test times and tested at an average age of five months, we find for ‘ seven days water curing that urea, formaldehyde, phenol and combinations thereof and sodium.eilicate are still comparable with plain cement; for fourteen days curing tested at five months, no comparative changes; for twenty- one days curing tested at five months, no comparative changes; and for twenty-eight days curing tested at five months, no comparative changes. The samples of cement mortars with.urea, formaldahyde and phenol admixtures treated as above show a general increase of about ten percent (101) in strength over plain cement mortars throughout the testing period. 59 A study of the specimens left to cure in the laboratory air shows for seven day test an average in- crease in strength of about ten percent (101) for urea, formaldahyde, phenol and combinations of these and magnesium sulphate over the average for plain cement. For fourteen day test these same admixtures are on a par or a little below that of plain cement. for twenty- one day test, except for phenol-urea, these admixtures are on a par’with plain cement, but phenol-urea shows a fifty percent (50%) increase over the plain cement average. ror twenty-eight day test the urea admixture has gained twenty percent (201) over the plain, the phenol-urea.maintains about a thirty-five percent (35%) increase and the rest of the above mentioned admixtures are about on a par with the plain cement. At the end of six months urea, formaldehyde, phenol and combinations of these are all leading the plain cement, with.phenol- urea about fifty percent (503) the better. After a study of the specimens that were air-cured then soaked in water and again left in air until tested, we find that for seven days in laboratory air, twenty-one days in water, then in laboratory air until tested at six months, the average of the urea, formaldehyde, phenol, combinations of these and magnesium sulphate were on a - par with the average of plain cement. For fourteen days in laboratory air, fourteen days in water, and then in laboratory air until tested at simeonths, magnesiumr sulphate and formaldehyde are on a par with plain cement, but the rest have fallen below. For twenty-one days in laboratory air, seven days in water, and then in labora- tory air until tested at six months, urea-formaldehyde and magnesium sulphate show one hundred percent (100%) gains over plain cement while the rest are on a par or a little better. rcr the twenty-eight days in laboratory air, sevendavs in water and then in laboratory air until tested at six.months, urea-formaldehyde, urea-phenol and _ formaldehyde show good improvements over the average plain cement; the rest are on a par'with the average, but one plain cement specimen is way ahead of the average of all (unexplainable except that the value could be in error). 61 CONCLUSIONS From a study of the results as related in the dis- cussion I conclude that: The admixture of urea, formal- ' dahyde, phenol, combinations of these, magnesium sulphate, and sodium silicate show a tendency to improve the strength of the cement. The admixture of phenol-urea for concrete that is to be placed where present curing methods are not economical will give an increased ultimate strength. The admixture of urea, formaldehyde, phenol or combinations of these will give a more reliable cement paste; test results show that these admixtures give a more consistent result than plain.cement paste. A glance at curves for test specimens eleven, eighteen and twenty-seven in com- parison to others will confirm this. 62 HECOMMEIUAwlONS I would recommend that optimum data be obtained for admixtures of urea, formaldehyde, phenol and combinations of these. The procurement of such data will take a long time, but I feel that the preliminary investigations in- dicate that these admixtures will, if properly applied, prove beneficial to the concrete structure. 10 11 12 13 14 15 17 6; BIBLIOuflAPh! Lea and Desch ”Chemistry of Cement and Concrete“ Text. Steiner D. "Belation.between chemical composition, manufacturing and physical properties of portland cement.” Zement #31 e 32 Rethy Andres 'Electro Concrete" Teknisk Tidskript Sept. 28 1935. Guttmann A. ”tensile Strength of Concrete" Zement #35 Aug. 29 1935 P 532. Gonnerman H. I. 'On Cement“ ‘Procedings A.3.2.l. Vol. 34 Part II P 244. Oil & Gas Ju 41 - n41 - Feb. 18 1943 p 48 &‘50 Research Journal V 30 n4 Apr. 1943 R.P. 1533 p 281-301 Concrete Journal V 51 n6 June 1943 Cement Mill See. p 184-6 Cement and Limelggngfacturing V 16 n7 July 1943 p ea e n n " V 16 n10 Oct. 1943 p 148 Pit and Quarry V 36 n3 Sept. 1943 p 67-10 Ae Se Te Me P2000. V42 1942 p 808.20 Smith G. A. J. Am. Conc. Inst. may 1932 V3 No. 9 Proc. 128 p 613-26 ”Effect of Celite on the Modulus of Elasticity of Concrete." Fruse r. I. "Effect of Vegetable Oils on Concrete” - Destructive Cone. Const. Engr. (Engl.) June 1932 V27 No. 6 p 346-51 Kleinlosel A. "Addition of Tricosal' Zement Aug. 1930 V19 No. 32 P 758-60 18 19 21 22 23 24 25 26 27 28 29 3O 31 32 33 6! Donovan, lerner and Stig Gierts ”Addition of Arsenious Oxide” Teknish Tidskrift (Swedish) April 1930 No. 5 p 41-49. Bogue and Lerch, P. C. A. Confirm.Bates results. Ieavitt, Gcwen and Jenness "Influence of Iron and Aluminum on mortar Strengths" Report Maine Technical Exp. Sta. 1929 Engr. less Record "Powdered Admixtures in Concrete" Rev. 21 1929 7103 so 21 p 816. "Influence of lagnesium Pluosilicate on Portland Cement” Zement (Germany) 1929 V18 p 1302-4e Ahlers J. G. 'Admixtures in Concrete“ Concrete Dec. 1929 V 35 Ho. 6 p 21. Plateman C. R. 'laterglass' Tonoid (Germany) 1930 Gordon A. and Sonza I. ”Effect of’Common Salt on the Tensile Stre h of Cement Mortars” Eyckerhoff and Hacken. [core and Dobrowsky I'Zn. Phosphate' Chem. Tec. 15 P 159-61 1942. Journal Am. Ceramic Soc. Vol. 25 p 129-41 1942. Journal Am. Soc. Inst. Vol. 5 lhrchsApril 1934 P 325. Journal Research lat'l Bureau of Stds. 30 p 281-301 1943. Chemical Abstracts Bates Grun 65 .' l.v 66 4 444 1 4 1 <4 <1 4 4 11 4 4. 4 4 4. 4<__ 4. a J . a . A. V 2. .1 . _ .Va.« .1 . 44 .1 . 2 ..v.. . . A . . .. ..le.\..<.2...2 . V.. 2 . ...4..1¢i 2. . .2.. 24 22 ~.« 242 \‘t... ...w ...AI .eV.2 . . .. ...... .22....2. 2.. .. . .. .. . . 2..... . .. .o_.$...\+.22.. ... . ..2 ..Tsl..21. ....rm . ...... J2... . . ....‘fia . 2.... 22. a . u. .. . .22... . .. ‘ ..2 .... . _ . . . 2 . 22.. V 2 .. ..«yo _. ...-.J... .2....... ..... . ....Lt...x. .. . e ... .2. ..2. . ...2..1..L..A.2 . ... 2...-.. ....h .222 .. 2 ..c..... . ... . . . . 2. . _ .... ...2a1.t .. v.......... .... .2 ..2......t.x..... . . .2. .. .. ... ~...... 2.... ... .... .. .. 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