CEMENT ADMIXTURE, CEMENT COMPOSITION AND CHEMICAL PRESTRESSED CONCRETE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To obtain a cement composition useful in the engineering works and building industries, excellent in swell characteristics and strength development and a chemical prestressed concrete having a high external pressure strength, hardly chipping at end parts. SOLUTION: This cement admixture contains a swelling substance composed of a mineral comprising CaO and CaSO4 as active ingredients obtained by heat-treating a blend of a CaO raw material and a CaSO4 raw material. The amount of the CaSO4 in the mineral is 10-50 pts.wt. in 100 pts.wt. of the total of CaO and CaSO4 . The swelling substance has <=100μm maximum particle diameter. The cement composition comprises a cement and the cement admixture. A cement mixture mixed with the cement composition is placed and packed into a mold and cured to give a chemical prestressed concrete.