CEMENT HARDENING RETARDER

PROBLEM TO BE SOLVED: To obtain a retarder having good function to retard the hardening of cement and not causing leaching by water, by blending a liq. contg. a metallic salt of a polybasic acid and a resin binder with a liq. contg. an urethane prepolymer. SOLUTION: A liq. contg. a metallic salt of a polybasic acid and a resin binder is blended with a liq. contg. an urethane prepolymer preferably in a weight ratio of about (1:0.1) to (1:1) to obtain the objective cement hardening retarder. The metallic salt is preferably a metallic citrate of formula I (where each of M -M is a divalent metallic element but all of M -M are not the same), in particular magnesium.calcium citrate of formula II. The resin binder is usually dissolved in an org. solvent or water is used as a dispersive medium therefor. The resin binder is preferably a vinyl acetate resin emulsion. The metallic salt is preferably used by 15-50 pts.wt. based on 100 pts.wt. of the resin binder. When the retarder is used, a good washed-out pattern is formed.