Effect of chemical admixture on property of fresh mortar using sludge water

Addition of sludge water as a part of mixing water had little influence on strength and durability of hardened concrete, but caused a slump decrease of fresh concrete. The decrease of slump was improved by addition of a certain set retarder such as gluconate into sludge water due to control of cement hydration. Some of polymers were also effective in improvement of slump. However hydration of cement was observed in those cases of polymers. Therefore it is presumed such the polymers improve slump not by hydration control effect but by another one.