| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cement admixture capable of reducing the using amount, and aiming at the improvement of its dimensional stability of cement for a long period and an expanding power by containing a specific cement expanding agent and urea. SOLUTION: This cement admixture is obtained by blending 50-95 pts.wt cement expanding agent which is obtained by heat-treating a blended material containing a CaO raw material, an Al2 O3 raw material, and a CaSO4 raw material, consists of a group of minerals consisting of free lime, hauynite and anhydrous gypsum as major component with molar ratios of 7.5-18CaO/Al2 O3 and 1.5-4CaSO4 /Al2 O3 , and has 2,000-9,000cm<2> /g Blaine value, with 50-5 pts.wt. urea. The cement composition is obtained by blending 99-85 pts.wt. cement with 1-15 pts.wt. above admixture. |
