MIXING AGENT FOR STIFF-CONSISTENCY CONCRETE AND PRODUCTION OF STIFF-CONSISTENCY CONCRETE USING THE SAME

PURPOSE:To provide a mixing agent which is excellent in dispersibility in cement and effective for maintenance of dispersion without causing hardening retardation by using a condensate of phenol, melamine or urea with formaldehyde in the presence of an amino-base polymerization. CONSTITUTION:At least one kind of compound selected from among phenol or its derivative, melamine or its derivative and urea is condensed or co- condensed with formaldehyde in the presence of an amino-based polymerization stopper. The objective mixing agent for stiff-consistency concrete is constituted of this produced condensate. As the used amino-based polymerization stopper, the compounds of formulas I, II and III are cited. In the formulas, X1 denotes H, 1-3C alkyl, carboxyl or its alkali metallic salt. Y1 denotes carboxyl and its alkali metallic salt. X2 denotes H and 1-3C alkyl. Y2 denotes carboxyl group and its alkali metallic salt. Z2 denotes H, 1-3C alkyl and CH2SO3M6. M5 and M6 denotes H and alkali metal.