Slump loss reducing material and cement composition using the same

摘要

PROBLEM TO BE SOLVED: To reduce the slump loss and to prevent an abnormal setting and excessive retardation of cement by blending the cement with specified amts. of silica fume granules of a specified diameter and a high performance water- reducing agent. SOLUTION: Silica fume granules of 50 m to 1.0 mm average diameter and a high performance water-reducing agent are incorporated to obtain the objective slump loss reducing material and 100 pts.wt. cement is blended with 3-15 pts.wt. silica fume granules and 0.8-3 pts.wt. (expressed in terms of solid) high performance water-reducing agent to obtain the objective cement compsn. Since the silica fume granules are used in combination with the high performance water-reducing agent, the change of slump with the lapse of time can be suppressed. The silica fume granules are obtd. by granulating fine powder of non-crystalline SiO2 generated at the time of producing metallic silicon or ferrosilicon in an electric furnace. As the high performance water-reducing agent, one, e.g. based on a polyalkylallylsulfonate or a melaminesulfonate is cited.