| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a cement additive in which the lowering of strength development is reduced even when the addition amount to cement is controlled to ≥10 mass%, and to provide a cement composition obtained by being admixed with the cement additive. <P>SOLUTION: The cement additive is obtained by pulverizing a heated material having a composition comprising, by mass, 40 to 75% SiO<SB POS="POST">2</SB>, 5 to 55% CaO and 5 to 30% Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, and having the percentage of glass of ≥50 mass%. The cement composition comprises the cement additive in ≤50 mass% in terms of an inner percentage to cement. The cement additive may comprise gypsum as well. <P>COPYRIGHT: (C)2012,JPO&INPIT |
