| 摘要 |
PROBLEM TO BE SOLVED: To obtain an expansive admixture exhibiting excellent expanding performance without generating pop-out after placing concrete, and a cement composition. SOLUTION: The expansive admixture comprises an expansive material as the principal component which is obtained by thermally treating a mixture comprising CaO raw material, CaSO4 raw material and one or more kinds selected from Al2O3 raw material, Fe2O3 raw material and SiO2 raw material, wherein the expansive material comprises free lime, anhydrous gypsum and one or more kinds selected from calcium aluminoferrite, calcium ferrite, hauyne and calcium silicate, where the free lime is contained by 35 to 60%, and characterized in that the content of calcium hydroxide is 1 to 15 pts. to 100 pts. of the expansive admixture. The cement composition comprises the expansive admixture and cement.
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