Development of new cement based matrices for safe disposal of hazardous metals: Cadmium and caesium

The innovative multicomponent matrix for immobilising cadmium and caesium introduced in this paper consists of belite cement, gismondine type NaP zeolite and nanoadditions. With this innovative design, the solid blend was able to absorb a high proportion of simulated radioactive liquid waste. Matrix integrity and effect of the high waste/solid ratio were assessed by X-ray diffraction analysis, while BET-N₂ surface area, pore size distribution and nanoporosity were determined with nitrogen adsorption isotherms. Matrices whose sole component was fly ash belite cement were used as a reference. This innovative material affords substantial social and environmental benefits, inasmuch as the cement used has a low CO₂ content and low heat of hydration. Moreover, both the cement and the zeolite can be synthesised ecoefficiently from an industrial byproduct, thereby eliminating the need to stockpile waste while preserving natural resources and placing valorised byproducts on the market.