Luftporenbildendes Zusatzmittel

PURPOSE: To obtain an air-entraining agent for cement composition with the variation in the amt. of air to be entrained by a cement composition reduced even if the content of unburned carbon in an admixture is fluctuated. CONSTITUTION: This air-entraining agent for a cement composition contains a fatty acid-base surfactant A consisting of a carboxylic acid as RCOOH (R is a 12-24C alkyl or alkenyl) or its alkali metal salt, a lower alkylamine or a lower alkanolamine salt and a nonionic surfactant B as R-substituted phenyl- O-(-CH2 CH2 O-)n -H (R is an 8-9C alkyl, and (n) is an integer of 1 to 50) or contains, besides the surfactant A and the surfactant B, further one or >=2 kinds selected from among alkyl sulfonates, alkyaryl sulfonates, higher alcohol sulfuric ester and rhodinate.