Powder drying shrinkage reducing agent for premixed mortar, premixed mortar and hardened cement

摘要

PROBLEM TO BE SOLVED: To provide a powder dry shrinkage reduction agent for premixed mortar suppressing dry crack by exhibiting dry shrinkage reduction effects, having no reduction of frost damage resistance and without deterioration of durability of a concrete structure even in cold district.SOLUTION: There is provided a powder dry shrinkage reduction agent for premixed mortar which is a fine powder by absorbing a polyoxy alkylene derivative (b) which is represented by the formula [1] and liquid at 25°C to an organic fine powder (a) with mass ratio of the organic fine powder (a) and the polyoxy alkylene derivative (b), ((a):(b)) of 20:80 to 60:40. RO-(AO)n-R[1], where Ris a saturated hydrocarbon group having 12 to 30 carbon atoms, saturated hydrocarbon group having 18 to 22 carbon atoms in Ris 70 mass% or more, Rrepresents one or more kind selected from a group consisting of a hydrogen atom and a methyl group, the hydrogen atom in Ris 70 mass% or more, AO is an oxyalkylene group having 3 and 4 carbon atoms, n is average addition molar number of the oxyalkylene group and n=1 to 50.SELECTED DRAWING: None