Development of one-part geopolymer binder produced from alkali fused boron mine tailings

The main purpose of this study is to investigate whether the boron mine tailings can be used as a raw material in producing one-part geopolymer binder by using the alkali fusion method. The boron mine tailings and alkali activator were calcined at 650 °C for 3h in a furnace. Both sodium hydroxide and sodium carbonate were used at different ratios as the alkali activator during the calcination process. The setting times, mechanical properties, sorptivity, and drying shrinkage of the one-part geopolymer mixtures based on alkali-fused boron mine tailings were investigated within the scope of this study. Furthermore, microstructural analyses were performed on one-part geopolymer paste samples to complement the obtained test results. The highest compressive strength value (24.2 MPa) was obtained from specimens activated with sodium hydroxide (4 % Na₂O by binder weight), while the highest flexural strength value (4.3 MPa) was obtained from the specimens with 20 % sodium carbonate. New crystalline phases such as merwinite, monticellite, sodium peroxide, and magnesium oxide were identified in the alkali-fused boron mine tailings. Ultimately, the main reaction product contributing to specimens' compressive strength development was identified as the riversideite phase.