A multi-level pore scale reactive transport model for the investigation of combined leaching and carbonation of cement paste

Abstract Cementitious materials in underground constructions are exposed to CO2 rich ground waters which leads combined carbonation and calcium leaching. Complex interplay between leaching, reaction changes transport pathways presents difficulty parameterizing continuum scale models a consistent way. Therefore, novel multi-level pore-scale reactive model is presented capture microstructure under Model explicitly resolves capillary pores phases with unresolved porosity as porous media. Governing equations solved using lattice Boltzmann method based solver chemical thermodynamic equilibrium. The two-dimensional parametric study on idealized microstructures revealed that carbon content pH of boundary solution strongly affects degradation rates, location thickness precipitated calcite layer. Furthermore, surface area plays dominant role tortuosity media rather secondary role. three-dimensional simulations virtual cement paste show rate exhibit non-linear behaviour square root time time. This implies simple empirical relations for prediction progression fronts not applicable use numerical inevitable.. developed qualitatively captures the development carbonation, leaching zonation observed experiments. Good quantitative agreement modelling experiments obtained initial stages. At later times, result experimental observations diverge significantly. discrepancy likely due lack consideration kinetics C-S-H dissolution precipitation.