Immobilization of Simulated Radionuclide ⁹⁰Sr by Fly Ash-Slag-Metakaolin–Based Geopolymer

In this work, the immobilization of simulated radionuclide ⁹⁰Sr by fly ash-slag-metakaolin–based geopolymer was investigated. It was found that the thermal stability (high-temperature and freeze-thaw resistance) of the geopolymer waste forms were better than that of cement. The geopolymer waste forms can acquire a compressive strength up to 10 MPa after 2 h calcination at 1000°C. Furthermore, the leaching tests revealed that the fly ash-slag-metakaolin–based geopolymer waste forms had lower cumulative fraction leaching rates of ⁹⁰Sr than that of cement. These results gave encouragement for the idea that the fly ash-slag-metakaolin–based geopolymers could be used as low cost and high efficiency host materials for the immobilization of radioactive wastes.