. Pa | [an a) _! a — — — List oe | at tae eat) a. Ps a tte - - we ese ¥ Vas mr ia ‘a Ee THESIS EC:mCUlUCO THE EFFECTS OF CHEMICAL SALTS ON CONCREYE. & Report oubmitted to the Faculty of the Michigan agricultural College By Kalter K. Willmen Candidate for the Degree of Bachelor of Science. June, 1921. THESIS TABLE OF CONTENTS. Page Introduction ®@eeempmeososeee@eeeet @©@6@@ @©@06088 080280 60@G@0%F €8 66 @ Specifications eeeovoeeenseeeson ee eeseeoeseeoeaneoeee @Geeeeeeee 8 @ Method of Pro cedure ©@eeeoeeseceeoeeeeneoeeeoenene eon eee eee 0 e686 6 8 4 Results - 7 Day Test @®eeeaeeoeeseeasnavaeeneneaeeneosneneasvnegeesee @ @ 7 Results -~ 28 Day Test @®espseeoeeeev@#~seo1eegs@*~osnseeseeesevseoeeeed @ Discussion of 7 Day TeStB ccccccccccccsccccccsece Ll Discussion of 28 Day Tests o¢e@2eee@8eeoeaeen ec eee eee 6 @ 13 1044455 PREFACE. For valued aid and advice on the work involved in this thesis, I am greatly indebted to Professor H. K. Vedder and C. Allen. We Ke Willman. THE EFFECT OF CHEMICAL SALTS ON CONCRETE BRIQUETTES. INTRODUCTION. Engineers are continually seeking the economical construction. The present construction age is an age of concrete and steel, the design meeting practically all oonditions that arise in building work. among the countless advantages of the present day concrete construction, strength, durability, beauty and simplicity of construction are highly important. The long life of the structure makes it economical, even tho the size of the members required to meet the stresses makes it a massive, heavy work. If it were possible to increase the strength of concrete by the addition of a cheap chemioal salt, the massive structures of today conld be lightened in weight and correspondingly beautified. It might also be possible to cheapen the cost of construction by a reduction in quantities. Experiments to date in cOnorete have singularly failed to disclose any such salt and it is my intention in this thesis to conduct and discuss a series of tests on concrete briquettes using solutions of the more cOmmon and cheapest salts in the mixtures. SPECIFICATIONS. (The specifications cited below are essentially those of the American Society for Test- ing materials.) 1. Peninsular cement was used thru-out the tests, 2. The residue on a No. 200 sieve shall not exceed 22% by weight, 3. The mix shall be 1:2 for the mortar briquettes, that is, one part of cement to two of sand, 4. Due to lack of Ottawa sand, bank sand was used in the mortars. Tests carried on proved thet bank sand oonteined 0.68% moisture and Ottawa sand .037% moisture which oalled for reducing the water .7% Tests on the tensile strength of mortars proved the tensile strength of bank sand to be 12% greater than Ottawa sand mortar. 5. All cement used in this thesis shall be passed thru a No. 3O mesh, 6. The ohemical salt solution shall be a 10% solution and this solution ehall be 10% by volume of the water used. 7. The following chemical salte shall be used and eight briquettes, (4 neat and 4 mortar) for the seven and twenty eight day tests shall be made. Sodium chloride, Sodium nitrate, Sodium sulphate, Potassium chloride, Potassium nitrate, Potassium bichromate, Magnesium chioride, Magnesium sulphate, Magnesium nitrate, Calcium sulphate, Calcium chloride, Calcium nitrate, Barium sulphate Barium chloride, Barium nitrate, i ee - METHOD OF PROCEDURE. I. NORMAL CONSISTENCY. I used Peninsular cement thru-out the teste, first getting its normal consistency by means of the Vicat needle. In this test various mixes of neat cement were made, mixing approximately 11/2 minutes. This mix was formed into a ball and tossed between the hands six times. It was then placed in the Vicat needle base and the surface flushed. The needle was quickly released and ellowed to press into the concrete. When the needle drops 10 mm. in 1/2 a minute, we have attained the normal consistency. If it drops more than 10 mm. the mix is too wet; if less than 10 mm. the mix is too dry. The amount of water required is expressed in percentage by weight of the dry cement. Results 600 gms. of cement 136 cc. H,0 135 B00 27% normal consistency for neat briquettes. For the mortar briquettes of standard 1:2 mix, it was found by compering a mix with the sand used to a mix with standard Ottawa sand that a normal consistency of about 12.5% was right. It. MANUFACTURE OF BRIQUETTES. I decided to give the manufactured briquettes seven and twenty eight day comparison tests with briquettes not containing chemical salts, said test to consist of breaking in the Rhiele tension testing machine for any comparative changes in strength. The mixes used were as follows: Neat cement briquettes . 27.5% Normal 700 gms. Peninsular cement consistency. 17.01 oc Hz0 ) ) ) 170.1 cc H3:0 ) ) In solution. 1.89 gms. Chem. Salt Mortar briquettes 1:2 mix. 467 gms. sand 233 gms. Peninsular cent, 78.75 oc. H,0 7.85 oo. H:0 ) ) In solution. .875 gms. Chem. salt ) I mixed four neat briquettes and four mortar briquettes, each containing the proper proportion of the ohemical solution for comparison with the ordinary oem nt and mortar briquette in a seven day test and the same number for a twenty-eight day test. These were allowed to set in the gang molds for twenty-four hours and then placed in chambers and covered with water. pective time periods, At the em of the res {on tes were broken in a Rhiele t ens the briquet Me results were tabulated and quet tes compute gequar the g verag® a end e inoh- machine. strength of each batch of bri tabulated. The results are in pounds per Salt Standard br. sod. Sod. Sod. Pot. Pot. Pot. Mag. Mag. Mag. Cal. Cal. Cal. Bar. Bar. Bare Chloride Nitrate Sulphate Chloride Nitrate Bichromate Chloride Sulphate Nitrate Sul phate Chioride Nitrate Sulphate Chloride Nitrate RESULTS - 7 DAY 490 470 515 595 530 450 500 590 480 600 520 485 550 590 470 680 NEAT 490 500 500 550 550 500 490 650 600 490 585 470 570 585 560 620 TEST - 505 515 500 620 560 460 540 490 510 550 590 450 520 4,70 500 510 476 630 470 500 630 510 535 5600 530 490 560 500 440 530 610 525 AY- 490 603 497 567 532 460 614 626 618 508 661 476 630 610 634 Salt Standard Br. Sod. Sod. Sod. Pot. POte Pot. Mag. Mag. Mag. Cal. Cal, Cal. Bare Bar. Bar. Chloride Nitrate Sulphate Chloride Nitrate Bichromate Chloride Culphate Nitrate Sulphate Chloride Nitrate Sulphate Chloride Nit Sate RESULTS ~ MORTAR 1 2 310 320 g20 315 335 346 400 386 3256 350 300 £305 410 370 390 320 290 300 310 330 360 360 390 360 310 330 260 310 290 320 280 310 7 pay TEST: 335 3456 555 350 376 290 340 350 330 330 370 360 300 300 300 320 330 310 320 376 340 310 390 380 315 320 385 360 320 315 2965 340 AVY: seh 325 378 343 g01 378 360 309 3235 388 566 315 297 301 316 1 Salt Standard Br. Sod. Sod. Sod. POte Pote Pot. Mag. Mag. Mag. Cal. Cal. Cal. Bar. Bar. Bar. Chloride Nitrate Sulphate Chloride Nitrate Bichromate Chloride Sulphate Nitrate Sul phate Chloride Nitrate Sul phate Chloride Nitrate pEsuLTs - 28 DAY TES? NEAT 1 a 3 610 660 616 660 650 56350 550 620 555 550 620 670 620 660 730 560 600 6650 730 640 710 680 630 590 750 660 760 590 600 560 560 636n 720 610 560 590 605 610 660 640 600 72° 720 +700 640 m0 640 740 690 540 600 650 500 655 740 610 700 630 600 580 620 670 670 720 644 668 665 623 600 617 705 627 718 570 601 588 621 656 683 103 Salt Standard Br. Sod. Sod. Sod. Pot. Pot. Pot. Mag Mage Mag. Cal. Cal. Chloride Nitrate Sulphate Chloride Nitrate Bichromate Chloride Sulphate Nitrate Sulphate Chloride Cal Nitrate Bare Bare Bare Sulphate Chloride Nitrate RESULTS - 28 DAY TEST 500 400 420 500 440 390 490 500 430 400 530 500 430 450 380 400 MORTAR 460 400 400 610 380 380 480 430 420 540 420 510 420 450 430 400 450 380 440 _ 460 400 3580 500 530 510 450 430 460 430 390 400 410 470 440 440 440 500 420 450 480 430 470 400 450 400 430 360 400 AV. 470 405 425 478 430 393 480 485 443 465 443 480 420 430 393 402 10 Ll DISCUSSION OF RESULTS 7 day test. The comparison of breaking strength of the standard neat briquette and the Sod. sulphate briquette showed the greatest increase, the neat sod. sul. briquette breaking for an average of 567 pounds per square inch as compared to the average of 490 for the standard neat briquette. The sod. sulphate mortar briquette broke at 378 as compared to 324 for the standard mortar briquette. The barium sulphate neat showed an increase of 54 pounds per square inch while the mortar showed a decrease Of 27 pounds per square inch. Such a discrepanoy is hard to explain satisfactorily unless it be improper mixing or handling of the testing machine, which would ooour should the revolving jaws stick. The other notable neat briquette increases were in those treated with Barium nitrate, pottasium chloride, said increases ranging from 20 to 40 pounds per square inch. fhe mortar briquettes treated with these same chemicals increased approximtely in proportion except in very few instances. It is my opinion that the only ohemicals that had an increasing effect on the briquettes were sodium sulphate and pottasium bichromate. This opinion is based on the fact that both the neat and mortar briquettes increased in strength and the briquettes broke at nearly the same pull thru-out. 32 13. DISCUSSION OF RESULTS 28 Dey Test. In the 28 day test, the only ohemical that seemed to increase the briquette's strength was potassium bichromate, the neat briquette having an average increase of 61 pounds per square inah and the mortar an average increase of 10 pounds per square inch. In other cases the strength of the neat treated briquettes would increase slightly while the strength of the mortar bricks would decrease and vice versa. In conalusion I would say that the results I obtained would hardly make it worth while to treat cement or concrete with a chemical salt. The salts are not at all readily soluble and the only one, potassium bichromate, that seemed to affect the briquette strength steadily is an orange colored salt and ite use colored the briquette. I do not think this is desirable. The inoreases in strength were not pronounced enough in any case to neke the treatment an economy. However, were it possible to run a larger number of tests, the wider range of results would tend to give a closer and mre accurate average of comparative etrengths and might prove conclusively that treatment with a certain chemical salt wuld increase the strength 14 of the concrete. Insofar as the quantity of calciun, Magnesium and sulphates in cement is limited now according to the A. S. of Testing Materials, it is Clear that their use would be detrimental. 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