A Study on the Retarding effects of Cememtn Mortar Setting

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J. Korean Ceram. Soc. > Volume 33(3); 1996 > Article

Journal of the Korean Ceramic Society 1996;33(3): 307.

시멘트 모르타르의 응결 지연 효과에 관한 연구

이재한, 이경희, 김홍기

명지대학교 무기재료공학과

A Study on the Retarding effects of Cememtn Mortar Setting

ABSTRACT

In following addition of 0.3, -0.6, 0.8, 1.0 and 5 weight percent MgSiF66H2O studies have been made of the setting and hardening characteristics of ordinary portland cement. MgSiF66H2O retarded the setting time of ordinary portland cement and extended the induction pariod of the hydration. In ordinary portland cement the setting characteristics were drastically altered especially at high MgSiF66H2O contents. Evidence was also obtained by the formation of a KSiF6 which was very fine particle. The results wee as follows. 1. Slump was slightly decreased when MgSiF66H2O added. 2. Setting time was retarded depending on the amount of retarding agent 2 to 8 hours 3. Compressive strength was almost same or some increased in comparision with opc. 4. When MgSiF66H2O was added to cement paste K2SiF6 were formed It was fine-sized distributed uniformly in cement grain and caused retardation of cement setting.

Key words: Cement mortar, $MgSiF_66H_2O$, $K_2SiF_6$, Inorganic retarder, Retarding mechanism