INFLUENCE OF POLYCARBOXYLATE WATER REDUCERS ON CEMENT HYDRATION

摘要

Hydration of cement in the presence of polycarboxylatc water reducers (PC) is the subject of ongoing studies. This paper discussed how PC copolymer affected hydration behaviour ofcement paste and what kind of influence would be cast to performance of cement mortars.Zeta potential measurements indicated that in spite of low electrostatic repulsive force, highdispersion ability of PC copolymer mainly comes from its steric hindrance. PC moleculesadsorbed on the surface of cement particles to reduce contact area between mineral particlesand water. After addition of PC, liquid phase electrical conductivity and pH values of cementpaste descended. PC molecules involved in cement hydration and dissociative ionsconcentration in liquid system decreased. Addition of PC also triggered an obviousretardation on cement hydration degree. The more added in, the lower hydration degree was.With slurry stiffening, its compressive strength enhanced gradually. Polycarboxylate waterreducers meet the requirements of high fluidity and high performance concrete.