Experimental study on the heat treatment reaction process of bentonite

This study focuses on enhancing the pozzolanic activity of bentonite through heat treatment to improve its compressive strength, while also considering its expansion properties for applications. Sodium bentonite was subjected to various temperatures and analyzed using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The results indicated that at 100 °C, adsorbed and interlayer water in montmorillonite was lost, and constitution water was eliminated at 700 °C. With further temperature increases, montmorillonite decomposes into an amorphous phase at 900 °C. At 1100 °C, the amorphous phase recrystallized into magnesium-aluminum silicate, which further decomposed into cristobalite. The study concludes that bentonite heat-treated at 800-900 °C can be effectively used as an additive in mining backfill materials to enhance compressive strength while maintaining its expansion properties.