To obtain the subject agent for reducing hexavalent chromium leach from hydraulic materials by including materials consisting mainly of hexavalent-reductive substances.
This agent comprises various kinds of reductive substances which are as follows: ferrous sulfate and/or ammonium sulfide and/or the like act as quick- acting reductive substance(s), while blast furnace slag, sulfur, peat, lignite and/or the like as slow-acting reductive substance(s); sodium thiosulfate and/or potassium thiosulfate is effective for insolubilizing hexavalent chromium over short/long period; for the reductive substances, one or more kinds can be combinedly used, however it is preferable to combinedly use quick-acting and slow-acting reductive substances, thereby exhibiting effect both at the initial stage and over a long period; the amounts of reductive substances except blast furnace slag to be used are each 0.1-10 pts.wt. based on 100 pts.wt. of a hydraulic material, being 5-900 pts.wt. based on the blast furnace slag; the reductive substances are used in the form of a hydraulic material through previously mixing into cement; besides, they are used by mixing into a grouting material or soil improving material, or used in producing cement paste, mortar, or concrete.
SASAKI KOTA
UCHIDA KOICHI
NOGUCHI MASAAKI
ISODA HIDENORI
HASHIMOTO MASAYUKI
HIRAO CHU
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