Influence of Composition of Sludge Water and Double Adding of Setting Retarder on Some Properties of Concrete

Abstract

Authors have been studying for several years as for the effective utilization of sludge water produced in ready mixed concrete plant containing cement and fine particles of aggregate. Nowadays, JIS A 5308 permits the usage under 3 percent as solids of sludge for the unit content of cement of new concrete. This study, in order to utilize the larger quantity of sludge water than that now allowed in the mixing plants, is to obtain the basical data on the properties of fresh concrete and of hardened concrete. In this study, the influence of composition of sludge and double adding of setting retarder has been discussed experimentally on the view points of slump, bleeding, compressive strength and drying shrinkage. From the results of this study, it was clarified that in the range of cement: fine sand is from 1:1 to 8:1, the composition of sludge has no large influence on the properties of new concrete. And the double adding of setting retarder has no good effect on the improvement of properties of sludge.