Alkali Resistance of Portland Cement PHILIP €1. DELANO1 AND PAUL J. WEBER2
EFFECT OF SODIUM SULFATE
A
LKALI resistance of cement and concrete is important in many parts of our country, especially in the West. In these places the soil carries a large amount of sodium sulfate and other alkaline salts which rapidly attack cement and may cause premature failure of concrete structures exposed to their action. Requirements for alkali resistance were a necessary part of the specifications for cement used in several important construction projects-for example, the Fort Peck Dam and the Colorado River Aqueduct-and alkaliresistant cement has become one of the important commercial types. Many attempts have been made to increase the strength or durability of concrete by admixture of various compounds to the cement or concrete mix. Some admixtures have proved beneficial, but most compounds tested (1) were ineffective or deleterious. Although sodium sulfate is among the materials generally regarded as objectionable in concrete mixes, the results in this paper show that addition of sodium sulfate markedly improves alkali resistance and that tensile strength is also increased, especially a t early ages. Admixture of sodium sulfate, therefore, may be desirable where greater strength or alkali resistance of concrete is required. Increased alkali resistance produced by admixture of small amounts of sodium sulfate is shown by the specimens in Figure 1. These are Merriman alkali-resistance test slabs prepared in an identical manner except that sodium sulfate equivalent to 4 per cent by weight of the cement was added in the mixing water of one set. Both sets of slabs were tested for resistance according to the Merriman method ( d ) , and the photographs show the condition of the slabs after 50 days. The untreated slabs failed after 20 days of exposure, while the test on the sulfated slabs was continued to 100 days without appreciable attack. The effect of sodium sulfate on tensile briquets is shown by the data in Table I. Here cement H was a commercial brand with high alkali resistance and cement L was a commercial brand with low alkali resistance. In both series the increased resistance of the sulfated briquets is evident.
Fort Peck Dam, Fort Pock, Mont.
A few alkali resistance tests were made with other compounds, but they were not beneficial in the proportions tried. Among those tested were calcium, iron, aluminum, and other sulfates; sodium carbonate, bicarbonate, oleate, stearate, and borate; and calcium chloride. Potassium sulfate did not increase either strength or alkali resistance. The effect of sodium sulfate is evidently specific and not typical of the alkali group. Windecker (3) patented the use of sodium sulfate with calcium hydroxide to produce a cement of high early strength. I n our experiments the combination was less effective for early strength than sodium sulfate alone, but alkali resistance was improved. I n evaluating any proposed admixture, the effect of the substance on the physical properties and strength of the
TABLE11. EFFECT OF SODIUM SULFATE ON PHYSICAL PROPERTIES OF PORTLAND CEMENT Normal oonsistency (Vipat), % ’ H10 Iiiitial time of w t , hr.:min. Final time of set, hr.:min. Tensile strength, Ib./ss.in. 1-day neat cement briquets 7-day neat cement briquets 28-day m a t cement briquets 7-day Ottawa briquets 28-day Ottawa briquets
Without iYazS0.r 25 0 3:35 6:OO
With 4% iTa6304 25.2 1:50 3:20
393 860
8% 393 49 1
857 937 lOOOf 456 547
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OF SODIUM SULFATE ON ALKALI RESISTANCE TABLEI. EFFECT OF PORTLAND CEMENT
Tensile Strength of 1 : 3 Ottawa Briqueta after Storage, Lb./Sq. In. Cement 5% NazSO4 AEb cc H 0.0 380 421 44 0.8 886 452 299 2.0 466 458 320 378 4.0 457 610 0.0 603 474 Completely disintegrated L 0.8 456 461 Complete!y disintegrated 2.0 4.36 444 Badly disintegrated 4.0 467 526 219 a Water, 28 days. b Water, 269 days. 0 Water, 28 days. followed by 10% NasSOr, 231 days. 4% NanSO4 addresa, 12061/s Riverside Drive, Tusoaloosa, Ala. Present address. Shields. N. Dak.
1 Present 2
Distilled water
ON NEAT CEMENTSLABS OF IWERSION FIGURE 1. EFFECT
FOR
692
50
D A Y S IN 4 P E R CENT SODIUM SULFATE SOLUTION
INDUSTRIAL A N D ENGINEERING CHEMISTRY
May, 1941
TABLE 111. EFFECTOF SODIUM SULFATEON STRENGTH OF PORTLAND CEMENT Tensile Stren th, Lb./Sq. In. ?-%ay 28-day 1-day 393 809 886 ... 725 937 lOOO+ 857 558 469 638 616 342 B NagRO4 0 393 491 NarSO4 4 456 547 C Nan801 0 164 605 772 NaISOh 2 323 670 868 368 Nan804 4 0 A Ineat cement briqueta; B I1 : 3 Ottawa briqueta: C sand-mortar mixes. b Setting time less than 30 minutes. 1
Testa A
Admixture, $7 ’’ Na&O4 0 NarSOa 3
... ... ... ...
... ...
...
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...
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... ... ... ...
... ...
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cement must be considered. The data in Tables I1 and I11 show that increased strength resulted from the use of
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sodium sulfate and that the increase was greatest a t early ages. In fact, the early strengths shown compare favorably with those of aluminous cements. Cement treated with sodium sulfate should be especially suitable for road building where high early strength and alkali resistance are desired. Other possible uses are sea structures, concrete in alkali regions, drainage ditches, and in general wherever alkali attack is expected. I n conclusion, cement of high alkali resistance and high early strength may be produced by addition of sodium sulfate to portland cement.
Literature Cited (1) Abrams, D. A.. Lewis Inat., BUZZ. 8, 12, 13 (1924-25) ; Jumper, C. H.. Proc. Am. Concrete Inst., 28. 209 (1932). (2) U S.Engineers Offioe, Specifications for Cement, Fort Peck D m Project. 1934. (3) Windecker, R. E.,U. 8. Patent 1,997,782(1935).
Fungicidal Potency of Quinoline Homologs and Derivatives Against Phymatot richum omnivorum NEIL E. RIGLER
GLENN A. GREATHOUSE
Texas Agricultural Experiment Station, College Station, Texas
Bureau of Plant Industry, U. S. Department of Agriculture, Washington, D. C.
HE cotton root-rot disease, caused by the soil. .....abiting fungus Phgmatotrichum omnivorum Shear (Duggar), is
8-Hydroxyquinoline is a well-known fungicide, and there is also the possibility that other compounds with a quinoline nucleus may be useful as fungicides, either as free bases in Twidespread in the Southwest. The parasite is known to oily materials or as salts in aqueous solution. Mixtures of have a large host range and causes much damage to cotton and other plants of economic these compounds are availimnortance. Not all d a n t s able from extracts obtained are’ susceptible, however, during refining of petroThe fungicidal potencies of isoquinoline, and the authors have been l e u m p r o d u c t s ; Axe, thirtcen quinoline homologs, 2- and 8engaged in an investigation Henson, and Schuhardt (1) of some of the chemical determined the germicidal hydroxyquinoline, a nitrogen base CleHzsN, aspects of resistance of variproperties of some repreand five fractions of bases from transous plants to cotton root sentative fractions. A comformer-oil extract were determined againat rot. It was found (9,6) p a r a t i v e s t u d y of t h e P. omnivorum. The most toxic comthat the toxicity, quantity, quinoline compounds should pounds permitted slight growth at 60 and location of alkaloids in afford an opportunity to certain resistant plants were observe in several related, p. p. m.; the most toxic fraction prevented fairly simple substances such that resistance in these growth at 40 p. p. m. The four aromatic some of the relations bespecies could be accounted fractions were more inhibitory than the for on the basis of their alkatween fungicidal activity nonaromatic one. Among both the comloidal content. The fungiand chemical s t r u c t u r e . pounds and the fractions, the potency cidal properties of quinoline The influence of fifteen homologs and derivatives quinoline homologs and detended to increase with increase in molecuare of interest because of rivatives and five fractions lar weight. 8-Hydroxyquinoline is more their relation to the alkaof nitrogen bases secured than six hundred times as potent as the 2loids, many of which contain from petroleum distillates isomer and apparently is the most toxic a quinoline or isoquinoline on the growth of P . omnicompound tested against this organism. .nucleus. vomm are reported here.
