| 摘要 |
PROBLEM TO BE SOLVED: To provide a concrete composition which is inexpensive, can suppress reduction in the strength of an obtained concrete cured product and occurrence of cracks in the concrete cured material by an excellent contraction reducing function, and can easily improve the quality of air entrainment, thereby imparting excellent freezing and thawing resistance and improving durability of the concrete cured product. SOLUTION: The concrete composition contains a cement and a contraction reducing agent for a concrete, the agent being essentially composed of a branched compound (A-1) expressed by general formula R<SP>1</SP>-[O-(A<SP>1</SP>O)<SB>m</SB>-R<SP>2</SP>]<SB>n</SB>. In the general formula, R<SP>1</SP>represents the R<SP>1</SP>derived from polyhydric alcohol expressed by R<SP>1</SP>-[OH]<SB>n</SB>, wherein n is 3 or 4; A<SP>1</SP>O represents an oxyalkylene group having 2 to 18 carbon atoms; R<SP>2</SP>represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; m represents an average additional molar number of the oxyalkylene group A<SP>1</SP>O and is 1 to 500; and when n is 3, the compound has a hydroxyl value of 10 to 60, and when n is 4, the compound has a hydroxyl value of 5 to 200. COPYRIGHT: (C)2011,JPO&INPIT
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