PURPOSE: To improve fluidity of concrete and to make slump loss small by regulating pH of the liquid phase of a kneaded concrete material mixed with water-soluble high molecular material to a specified range.
CONSTITUTION: In case of producing concrete mixed with water-soluble high molecular material e.g., cellulose derivative such as carboxymethyl cellulose, acryl-series compd. such as polyacrylamide and polyethyleneseries compd. such as polyethylene oxide, fluidity is improved by using cement wherein Na and K eluted into the liquid phase of kneaded concrete material are incorporated at ≥0.30wt.% expressed in terms of (Na2O+0.658 K2O) in whole quantity or one part of cement and fineness is ≥4000cm2/g Blaine's value and using an admixture incorporating a water reducing agent and alkali components such as rust preventives and also using recovery water generated at a time for producing cement and concrete products and thereby regulating pH of the liquid phase of the kneaded concrete material to ≥12.5 preferably ≥12.8.
FUJIWARA HIROMI