| 摘要 |
Provided is a cement admixture which gives cured cement concrete that imparts excellent non-corrodible properties to the reinforcing bars present therein, has resistance to external infiltration of chloride ions, and can be inhibited from becoming porous because Ca-ion eluviation occurs little and that has self-healing ability. Also provided is a cement composition. The cement admixture is characterized by comprising a calcium ferroaluminate compound which is based on CaO, Al2O3, and Fe2O3, has an Fe2O3 content of 0.5-15 mass%, and has a CaO·2Al2O3 structure, the CaO/Al2O3 ratio being in the range of 0.15-0.7 by mole. It is preferred that the admixture have a degree of fineness of 2,000-7,000 cm2/g in terms of Blaine specific surface area and that a latent hydraulic substance and/or a pozzolanic substance (pozzolanic substance and the like) be used in combination with the calcium ferroaluminate compound. The pozzolanic substance and the like preferably comprise one or more substances selected from a group consisting of ground granulated blast furnace slag, fly ash, silica fume, metakaolin, incineration ash of pulp sludge, incineration ash of sewage sludge, and waste glass powder. It is preferred that the ratio of the calcium ferroaluminate compound to the pozzolanic substance and the like be from 10/1 to 1/10 by mass. The cement composition comprises a cement and the cement admixture. |
