Immobilization of sulfate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam waste: Evaluation of the final waste form under freeze–thaw treatment

A new polymer–cement composite matrix for solidification and stabilizing of low‐ and intermediate level radioactive sulfate waste, containing high concentration of sulfate as sodium salt (113.16 g/L), had been developed at the inorganic applied chemistry unit, radioisotope department, Egyptian atomic energy authority. The proposed composite is based on ordinary Portland cement and expanded polystyrene recycled from foam wastes. The integrity of the reached final waste forms (polymer–cement composite immobilizing sulfate wastes simulate) was evaluated after subjecting to freeze–thaw (FT) treatment. The cycling was performed for the final waste form at the end of 28 days curing period between (−20°C ± 1) and (60°C ± 1) for 180 days. Mass changes, compressive strength, porosity, and bulk density were determined for the solid blocks at the end of definite increasing FT cycles. To evaluate the changes in the internal structure accompanied the FT cycling, Fourier‐transform infrared, X‐ray diffraction, thermogravimetry, and scanning electron microscopy tools were used. Based on the data obtained, it could be stated that the proposed polymer–cement composite can withstand the aggressive conditions exist during the disposal process and candidate it can be used adequately for incorporating the sulfate waste concentrate originated from the boiling water reactors. POLYM. COMPOS., 38:637–645, 2017. © 2015 Society of Plastics Engineers