Effects of comb-like PCE and linear copolymers on workability and early hydration of a calcium sulfoaluminate belite cement

Abstract

Fluidity control and setting adjustment are two critical issues for practical applications of calcium sulfoaluminate cement because of rapid hydration. A commonly used comb-like polycarboxylate superplasticizer (PCE) and linear copolymers (PAS) of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) with varied monomer ratio were synthesized to study their impacts on fluidity and early hydration of calcium sulfoaluminate belite cement (CSAB). Results show that the linear PAS polymers are very effective in dispersing fresh cement pastes (fcps) and effectively inhibit early hydration of the cement. More AA unit in the PAS molecules leads to stronger inhibition effect on cement hydration. Compared with the PAS polymers, PCE exhibits almost no inhibition effect on cement hydration despite the high initial dispersibility. Thus, cement pastes containing PAS polymers exhibits excellent fluidity retention compared with the PCE containing fcp due to strong retardation effect of the PAS polymers on early formation of AFt crystals.