Formulation and durability of a geopolymer based on metakaolin/tannery sludge

In this study, tannery sludge was used as a partial replacement material for a geopolymer. The best raw material composition of the geopolymer and durability of the solidified product were studied. Solidification effect was analyzed via compressive strength and total concentration of chromium leached. Its durability in terms of high-temperature resistance, acid/base resistance property, and resistance to acid rain erosion was studied. Through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric Differential Thermal Analysis (TG-DTA) and scanning electron microscopy (SEM), the compressive strength and total concentration of chromium leached in different environments were analyzed. The results show that the mechanical properties of the solidified product were optimal when the silica/alumina mole ratio and sodium oxide/silica mole ratio were 2.45 and 0.37, respectively. The optimal raw material ratio of the above-mentioned product was used to synthesize a geopolymer containing 20% tannery sludge, with the solidified product showing high durability, as indicated by its good high-temperature resistance, high resistance to acids and alkalis, and great resistance to acid rain erosion.