Compatibility between a polycarboxylate superplasticizer and the belite-rich sulfoaluminate cement: Setting time and the hydration properties

•Polycarboxylate superplasticizer (PCS) was introduced to adjust the setting time of belite-rich sulfoaluminate cement.•Setting time was greatly relevanted to the amount of polycarboxylate superplasticizer.•PCS decreased the compressive strength at 1 day meanwhile increased the compressive strength at 28 days.•PCS makes the morphology of pores in the cement pastes transformed from macropores to micropores at 28 days remarkably.

Belite-rich sulfoaluminate cement, a novel type of cement, has been synthesized via a calcined process. This paper presents an experimental study on the effects of polycarboxylate superplasticizer on the setting time and the mechanical performance of this type cement to solve the problems of quick set at an early stage. The results indicate that the setting time depends upon the amount of the superplasticizer, especially for the initial setting time. The presence of the superplasticizer can delay the initial setting time remarkably when the dosage reaches 0.075%. The influence of the superplasticizer on the strength development at different hydration stages presented different results, observed by a decreased strength at an early stage and an increased strength at 28 days. X-ray diffraction (XRD) analysis, mercury intrusion porosimetry (MIP) characteristics and scanning electron microscope (SEM) images of the pastes were also studied to investigate the mechanism of compatibility between the superplasticizer and the cement.