A CEMENT ADDITIVE, A CONCRETE COMPOSITION AND A STRUCTURE USING THE SAME

A cement additive composition for preventing discoloration of the surface of concrete, comprising a cement additive (a) and a water-reducing admixture (b), the additive (a) comprising a mixture of compounds represented by the general formula (1) : R1O(AO)n1H .multidot. (1) (wherein R1 is a C1-6 alkyl group, A is an ethylene group and/or a propylene group, and n, is a number of 1 or more), containing all the compounds satisfying n1 = 2 to 6 in a total amount of not less than 40 % by mass, and having an average n1 of 1.5 to 10, a molecular weight distribution Mw/Mn of not less than 1.05, a Z average molecular weight Mz of not less than 200 and a ratio of (a) : (b) by mass of (5 to 99.5) : (95 to 0.5). It can prevent the discoloration of the surface of concrete.