Comparative performance of cement and metakaolin based-geopolymer blocks for strontium immobilization

Abstract

This paper presents the comparative performance of ordinary Portland cement and metakaolin-based geopolymer blocks for strontium immobilization. The geopolymer solidified blocks had better leaching resistance in deionized water, sulfuric acid, magnesium sulfuric and acetic acid buffer solutions than the cemented blocks. Meanwhile, the geopolymer solidified blocks exhibited lower compressive strength loss after freeze-thaw cycles and high-temperature tests. The more dense and compact structure of the geopolymer specimens is more beneficial for the retention of the strontium radionuclide. Most of the strontium radionuclide within the geopolymer and cement solidified blocks may be incorporated into the amorphous gels. It could be concluded that the metakaolin based-geopolymer matrix exhibited much better solidification performance and appeared to be more suitable for radioactive waste immobilization.