Prediction of Filtration Properties of Portland Cement Concrete Based on the Results of Calibration of the Basic Hydration Simulation

Ordinary Portland cement-based materials are considered in many concepts of geological isolation of Radioactive Waste (RW) for the design of Engineered Safety Barriers (ESB). The safety functions of cement-based EBS consist of limiting the access of groundwater to the near zone of the Geological Disposal Facility (GDF) of RW and reducing the rate of migration of radionuclides due to diffusion. These factors can be described by the hydraulic conductivity and effective diffusion coefficient values, mainly determined by the porosity of the barrier material.

The article presents experimental data used to calibrate the basic hydration simulation of Ordinary Portland Cement (OPC) concrete considered as a potential material for an engineered barrier in the GDF in the “Yeniseisky” site of the Nizhnekansky crystalline rock massif in the Krasnoyarsk region based on the simulation results using PhreeqC 3.7.3 software.

As the result of the current work phase composition of the initial binder and concrete, as well as the chemical composition of water added to the concrete mixture, were established. The obtained data were used for the parameterization of the basic simulation of OPC concrete mixture hydration.

OPC concrete porosity, hydraulic conductivity, and pH of the pore solution were calculated. Obtained values wereconsistent with the analytical data collected during the experiments, and the values of the effective diffusion coefficients of the radionuclides that pose the greatest threat to the biosphere and are expected to be isolated in the GDF were predicted.