CEMENT ADMIXTURE, CEMENT COMPOSITION AND MANUFACTURING METHOD OF MORTAR OR CONCRETE PRODUCT

[PURPOSE] TO PROVIDE A CEMENT ADMIXTURE WHICH CAN IMPROVE FALSE SETTING CAUSED BY RAPID SOLVING RATE OF NATURAL ANHYDROUS GYPSUM AND STABLY ENSURE HIGH-STRENGTH DEVELOPMENT PERFORMANCE WITHOUT LIMITING THE TYPE OF A WATER REDUCING AGENT, A CEMENT COMPOSITION USING THE ADMIXTURE AND A MANUFACTURING METHOD OF A MORTAR OR CONCRETE PRODUCT USING THE ADMIXTURE. [CONSTITUTION] IN A CEMENT ADMIXTURE HAVING ONE OR MORE TYPES OF MAIN COMPONENTS CHOSEN FROM NATURAL ANHYDROUS GYPSUM, BURNT CLAY MINERAL, CLAY MINERAL, HYDRATED LIME AND CALCINED LIME, WHEN SAMPLED SO THAT AN AMOUNT OF NATURAL ANHYDROUS GYPSUM IN THE CEMENT ADMIXTURE CORRESPONDS TO 1G AND PUT IN CONTACT WITH 100G OF 0.05% NA2HPO4 AQUEOUS SOLUTION AT 20 °C FOR 1 HOUR, THE SO4 IONIC CONCENTRATION IN THE AQUEOUS SOLUTION INDICATES A SOLVING RATE OF 0.027 TO 0.30 MASS%/HR. MOREOVER, THE ABOVE CEMENT ADMIXTURE IS ADDED TO A CEMENT IN THE CEMENT COMPOSITION. FURTHERMORE, IN A MANUFACTURING METHOD OF A MORTAR OR CONCRETE PRODUCT, A MORTAR OR CONCRETE MATERIAL TO WHICH THE ABOVE CEMENT ADMIXTURE IS MIXED IS NORMAL-PRESSURE STEAM-CURED.