B₂O₃-modified geopolymer and its liquid-phase sintered products for immobilization of strontium

Sr-containing ceramic products produced from geopolymer, (Na, Sr)-GP, have been reported as excellent candidate materials for the immobilization of radionuclide 90Sr, despite sintering temperature at 1200°C. In this work, the product possessing the best immobilization performance (leaching rate of 1.29% for Sr²⁺) can be produced at 1000°C in the method of liquid-phase sintering via the addition of fluxing agent B₂O₃ at 2.0 wt% in the geopolymer precursor. The mechanical properties of the geopolymer precursor (Na, Sr)-GP were also enhanced via the promotion role of B₂O₃ to geopolymerization. It was revealed that the overall anti-leaching ability of the Sr-containing ceramic product not only depends on the microstructure of the loading substrate but also can be affected by the chemical state of radioactive strontium retention in the loading matrix.