Uptake of chloride and iso-saccharinic acid by cement: Sorption and molecular dynamics studies on HCP (CEM I) and C-S-H phases

Abstract

The uptake of chloride and ISA by cement in the degradation stage I was investigated with a combination of sorption experiments and MD simulations. The retention of Cl-36 decreases with increasing [Cl-](tot) in cement pore water. The uptake of Cl-36 is dominated by sorption phenomena and the formation of the Friedel's salt at low and high [Cl-](tot), respectively. ISA sorbs moderately on HCP, and a one-site Langmuir isotherm was used to satisfactorily model the sorption data. MD simulations highlight the key role of Ca in the binding of ISA to C-S-H. This work provides a sound basis for predicting the uptake of chloride and ISA by HCP in the context of L/ILW repositories, together with new insights for the mechanistic understanding of ISA uptake.