Moisture Transport Properties of Cement-Based Materials for Engineered Barriers in Radioactive Waste Disposal

Abstract

This paper reviews the multi-phase modeling of moisture transport process in pore structure of cement-based materials used as engineered barriers in radioactive waste disposal. The emphasis is put on the fundamental relationship of moisture isotherm and the related hysteresis phenomenon. A typical cement-based material is retained for study and its properties for moisture transport were measured. The pore structure was characterized by mercury intrusion porosimetry (MIP) and gravimetry method. The moisture isotherm was measured in laboratory by humidity equilibrium method and the predicted isotherm from MIP pore structure is confronted with the measured isotherm. Afterwards, a numerical scheme is set up for the multi-phase transport model and the model is applied to the moisture transport process of engineered barriers exposed to natural drying and drying–wetting cycles. It is observed that the ratio between drying and wetting periods has strong influence on the depth of surface convection zone.