SLUMP LOSS-REDUCED TYPE CEMENT ADMIXTURE

摘要

PURPOSE:To obtain a cement admixture effective in preventing the slump loss by using a mixture of two kinds of copolymer salts having a high and a low molecular weights in those of light oil component consisting essentially of indene and an unsaturated dicarboxylic acid anhydride and a salt of a formaldehyde condensate prepared from an oil fraction consisting essentially of (alkyl)naphthalenes in combination. CONSTITUTION:A cement admixture is obtained by using the following two components (A) and (B). (A) A mixture of at least one selected from the group consisting of alkali metallic salts, ammonium salts and amine salts of copolymers, prepared by reacting a light oil fraction consisting essentially of indene with an unsaturated dicarboxylic acid anhydride containing olefinic double bond and having 1500-4000 number-average molecular weight measured by gel permeation chromatographic(GPC) analysis with at least one selected from the group consisting of alkali metallic salts, ammonium salts and amine salts of the copolymers, obtained by a method similar to that described above and having 6000-20000 number-average molecular weight. (B) At least one selected from the group consisting of alkali metallic salts, alkaline earth metallic salts, ammonium salts and amine salts of compounds prepared by sulfonating an aromatic hydrocarbon-containing oil consisting essentially of naphthalene and/or alkylnaphthalenes and then condensing the sulfonated oil with formaldehyde.