Synthesis and Evaluation of Polycarboxylate-Type Superplasticizers with Different Carboxylic Contents Used in a Cement System

Abstract

A series of polycarboxylate-type superplasticizers (PCs), possessing almost the same degree of polymerization and different molar ratios of methacrylic acid (MAA) to methyl poly (ethylene oxide) methacrylate (MPEOM), were synthesized, and the effect of carboxylic content on the fluidity, water-reducing ratio, bleeding, setting time, mechanical strength, and rheological behavior in a cement system was systematically evaluated in this paper. When the molar ratio of MAA to MPEOM is 3.6:1, PC has better performance for improving the dispersing ability to cement particles, reducing the apparent viscosity of cement suspensions, increasing the water-reducing ratio, and improving the mechanical strength of hardened mortar over PC with other molar ratios. In addition, the more carboxylic content of PC, the greater retardation effect of cement paste, and the higher the bleeding water percentage (BWP) of fresh mortar.