| 摘要 |
PROBLEM TO BE SOLVED: To prolong a hardening time and to reduce metal corrosion, by mixing a cement with a phosphonocarboxylic acid or its salt. SOLUTION: This cement composition contains particles capable of reacting in the presence of an aqueous liquid medium and aggregating to form a solid mass (lump) and provides effective hardening retardation, corrosion prevention of iron and steel and improvement in dispersion, deflocculation, etc., by adding a phosphonocarboxylic acid or its salt in an amount to modify the formation of the mass to the cement composition. Sodium or potassium phosphonocarboxylate is preferable as the retarder. The most preferable phosphonosuccinic acid is a phosphonated telomer of active olefin of the formula H[CHRCHR]n -PO3 M2 (one or more of Rs are COOH and the others are each H, COOH, OH, an alkyl, etc.; 1<(n)<200; M is H or a cation). The retarder in an amount of 0.01-5 wt.% based on the total solid content weight is made present in a cement. |
