Comparative study of immobilization and mechanical properties of sulfoaluminate cement and ordinary Portland cement with different heavy metals

There have been limited studies on the hardening of cement containing different heavy metals owing to differences in solidification effect. The leachability, setting time, and compressive strength of sulfoaluminate cement (CSA) and ordinary Portland cement (OPC) mixed with different concentrations of Cr(NO3)·9H2O, Pb(NO3)2, Cd(NO3)2·4H2O solution were studied and the hydration products were analyzed using XRD and SEM. The results suggest that CSA immobilized Pb2+ and Cd2+ efficiently, while OPC solidified Cr3+ and Cd2+ well. Cd2+ prolonged the setting time of CSA and Pb2+ remarkably delayed that of OPC. There was only a slight influence of Cr3+, Pb2+, and Cd2+ on the compressive strength of CSA or OPC.