PROBLEM TO BE SOLVED: To rapidly reduce the fluidity of a cement concrete by adding an alkali metal salt to the cement concrete containing a high-performance water- reducing agent. ;SOLUTION: Carbonate or sulfate of an alkali metal is added to a cement concrete containing a high-performance water-reducing agent such as a naphthalenesulfonic acid-based water-reducing agent, a melaminesulfonic acid- based water-reducing agent and a polycarboxylic acid-based water-reducing agent. As the result, the activities for dispersing a cement or the like, possessed by the high-performance water-reducing agent are reduced momentarily, and the fluidity is lost. The cement concrete with the added alkali metal salt can be constructed without causing sagging when placing the cement concrete on a slant placing site, and also is effective when the fluidity is required to be lost just after the placing without damaging the transportability of the cement concrete with the fluidity. The cement concrete enables the force feed by a pump, or the like because the fluidity of the cement concrete before adding the metal salt can be improved, and the fluidity of the cement concrete is rapidly reduced by adding the metal salt just before the placing.;COPYRIGHT: (C)2000,JPO
展开▼
