Mixtures of 12 commercial portland cement clinkers and water were filtered at 7 minutes and at 2 hours after m ixing, and the chemical composition, pH, conductivity, surface tension, and density of the extracts were determined. The effects on the composition and physical properties of the extracts, produced by the addition of small amounts of various materials to the pastes, were studied in parallel experiments. The added materials included gypsum, which was used in preparing the cements from the clinkers, calcium chloride, calcium ace tate, fluosilic ic acid, sucrose, T D A, tannic acid, and triethanolamine.In the majority of the extracts, soda and potash were present in greater amounts than an y of the other dissolved oxides. Relatively high concentrations of sulfate occurred in the extracts of the clinkers that contained the larger amounts of potash. The lime concentration and basicity of the extracts were largely determined by the amounts of alkali oxides present. The concentration of silica corresponded approximately to the reported solubility of silica in lime solutions. Low concentrations of oxides of the R 20 a group were found except in extracts from pastes con taining the added organic materials.

Data presented were ohtainecl in studies of three t ypes of c, ommercial cements, including two low-heat Boulder Dam, two high-early-strength, and six standard pDrtland cements. Portions of each .of the cements .of the latter two t ypes were steam prehydrated so that the ignition losses were i ncreased for each cement to approximately 3 and 5 percent, respectively . The heats of hydration and als.o the compressive strengths of concrete specimens made of the untreated and of the prehydrated cements were determined for the ages of 7, 28, 90 days, and 1 year. Three curing conditions were used; continuous storage at 70 0 F, continuous storage at 150 0 F, and three respective combinations of storage at 70 and 150 0 F. Chemical analyses, calculated compound c.ompositions, and specific surfaces are given. The heats of hydration and compressive strengths were bDth reduced by prehydration of the cements, the 5 percent prehydration causing greater reductions than the 3-percent. At the later ages the heats of hydration obtained at continuous 150 0 F curing were lower than the heats .obtained at continuous 70 0 F curing. The strengths at later ages, however, were not greatly affected by the curing temperature. The 5-percent prehydrates of standard portland cements had heats of hydration that would pass the lowheat specificatiDns for Boulder Dam cements. The expansion results on specimens made of the untreated and of the pre hydrated cements stored in sodium sulfate solutions show that with the exception of the cements high in tricalcium aluminate the prehydrations increase the resistance t.o the action of sodium sulfate. The 5-percent prehydrates had greater resistance to the sulfate action than the 3-percent.CONTENTS

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Studies were made of the effects of added materials on the properties of a group of portland cement clinkers representing standard-portland, moderateheat-of-hydration, high-early-strength, Bulfate-resistant. and white cements. The materials used were gypsum, sugar, calcium chloride, TDA (grinding aid), tannic acid, triethanolamine, calcium acetate, and fluo silicic acid. The effects were judged by comparing the results of tests of specimens of clinker pastes containing the materials under investigation with the results of similar tests of the clinker pastes to which nothing had been added. It was found that although some of the materials caused large changes in the behavior of the clinker pastes during their early history, these effects largely disappeared thereafter. Few of the substances had much effect on the r es ults of tests performed at 28 days. No tests were made to evaluate the effect of the added materials after longer periods. CONTENTS

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