Effect of Carboxylic Acid on the Hydration of Plaster of Paris under Alkalinity

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J. Korean Ceram. Soc. > Volume 31(10); 1994 > Article

Journal of the Korean Ceramic Society 1994;31(10): 1107.

알카리성 분위기에서 소석고의 수화에 미치는 카르복실산의 영향

이승헌

군산대학교 재료공학과

Effect of Carboxylic Acid on the Hydration of Plaster of Paris under Alkalinity

ABSTRACT

Although various theories have been presented on the mechanism of setting retardation of plaster in addition to organic admixtures. The purpose of this paper is that Hydration studies of plaster of paris in the presence of carboxylic acids under alkalinity are examined in the coordination chemistry. Setting of plaster of paris is retarded by the addition of carboxylic acids except oxalic acid. And setting of plaster of paris contained 5 wt% of Ca(OH)2 is also retarded by the addition of above-mentioned carboxylic acids. The degree of retarding effect under alkalinity is found to be a function of the number of the functional group and the length of carbon chain of carboxyl acids. These reasons are attributed to the soluble complex formation, that is calcium complex formation between calcium ion and carboxylic acids. The author's proposal was confirmed by the results of electrical conductivity measurement. The formation of calcium complex was surpported by IR spectra.