High Temperature Treatment to Improve Hydrolytic Stability of Mine Tailing-Based Geopolymer Bricks

Reuse of mine tailings is a growing area of research, and one possible reuse strategy is the creation of geopolymer bricks. Geopolymerization uses a strong alkaline solution to break down the source material into alumina and silica monomers, which are then consolidated and cured into a strong, solid sample. However, a well-known and existing challenge in performance of tailings-based geopolymers is the poor hydrolytic stability (i.e., durability in water). To improve this property, a high temperature treatment was applied to geopolymers made from 85% gold mine tailings and 15% fly ash type F. The geopolymer bricks were heated to 600°C for 6 h, which densified the pore structure and improved the performance of samples in water. The compressive strength retention was improved from 55% to 83%, and samples exhibited nearly zero mass loss during water immersion for seven days. This technique can be generalized to geopolymers made from any type of low-reactivity source material, though further testing is needed to determine the beneficial effect for other mix designs.