Synthesis and rapid cement hardening evaluation of polycarboxylate superplasticizers incorporating ester groups in their backbone chain

Abstract

AbstractA new water‐soluble, hydrolyzable polyethylene glycol di‐mercaptoacetate (PGM) was synthesized as a chain transfer agent. Subsequently, an early‐strength polycarboxylate superplasticizer (ESPC) was successfully prepared by using PGM as a chain transfer agent, along with acrylic acid, sodium methylallyl sulfonate (SMAS), and isoprene oxy poly(ethylene glycol) as comonomers. The effect of the ESPC on cement particles was systematically investigated. The fluidity, setting time, and compressive strength were measured to evaluate the performance of the ESPC and compared with those of a conventional polycarboxylate superplasticizer (PCE). The setting time of the ESPC can be shortened by 40 min in comparison with the PCE, and the compressive strength at 24 hr of setting time is increased by 5 MPa. In addition, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy characterization were performed to investigate the effect of the ESPC on cement hydration from a microscopic level. Furthermore, the hydration heat was determined to investigate the interactions between the ESPC with the cement particles. It was found that if ester groups were introduced into the backbone chain of the ESPC and subsequently hydrolyzed, the ESPC was readily adsorbed onto cement particles. This enhanced adsorption improved the microstructure of the cement hydrate and accelerated the cement hydration process.