Stabilization/Solidification of Strontium Using Magnesium Silicate Hydrate Cement

Magnesium silicate hydrate (M-S-H) cement, formed by reacting MgO, SiO2, and H2O, was used to encapsulate strontium (Sr) radionuclide. Samples were prepared using light-burned magnesium oxide and silica fume, with sodium hexametaphosphate added to the mix water as a dispersant. The performance of the materials formed was evaluated by leach testing and the microstructure of the samples was also characterized. The stabilizing/solidifying effect on Sr radionuclide in the MgO-SiO2-H2O system with low alkalinity is demonstrated in the study. The leaching rate in a standard 42-day test was 2.53 x 10(-4) cm/d, and the cumulative 42-day leaching fraction was 0.06 cm. This meets the relevant national standard performance for leaching requirements. Sr2+ was effectively incorporated into the M-S-H hydration products and new phase formation resulted in low Sr leaching being observed.