Leaching resistance of hazardous waste cement solidification after accelerated carbonation

• We developed a multi-physics and –phase model for supercritical carbonation and leaching of cement based materials.
• We conducted experiments to validate the model.
• We investigated the impact of carbonation on the retention capacity of cement.
• We studied the effect of various physical properties on the leaching process of Sr and Cs ions.

When cement-based materials are carbonated, some of their physicochemical properties are changed, which includes reductions of porosity by 20% and pH from 12 to 13 to 8–9. These changes can enhance the retention ability of cementitious solids containing hazard waste. This research studied the effect of carbonation on the leaching resistance of hazardous waste cement solidification. The finite element software COMSOL Multiphysics was used to simulate the process of accelerated carbonation and the effect of carbonation on leaching. Laboratory tests were conducted to validate the numerical models. Parametric studies from the numerical simulations revealed that carbonation could significantly improve leaching retention capabilities of cementitious solids containing hazardous wastes.