CEMENT ADMIXTURE, PREPARATION METHOD THEREOF, AND COMPOSITION USING THE ADMIXTURE

PURPOSE: A cement admixture, its preparation method and a mortar or cement composition using the admixture are provided, which is economical, can be produced massively and has good strength. CONSTITUTION: A cement admixture is prepared by wet-pulverizing at least one material selected from natural kaolin and halloysite with 200 mesh sieve; molding the wet pulverized material to the shape of sphere whose diameter is 5-30 mm or cylinder whose diameter is 5-30 mm and whose length is less than two times of the diameter and drying it; sintering the molded body at the temperature of 750-900°C; and dry-pulverizing the molded body. Preferably the mean size of dry pulverized one is in the range of 4 to 8 mm and its maximum size is less than 70 mm. The cement admixture is such that its ratio of alumina to silica is 1.0:1.2 to 1.0;1.6 and its density is 2.5-2.6. The mortar or cement composition comprises 5-20 wt.% of the cement admixture based on the total amount of cement.