A versatile pore-scale multicomponent reactive transport approach based on lattice Boltzmann method: Application to portlandite dissolution

Cement is one of the important construction materials in waste disposal system and changes in properties of due to interaction of surrounding environment which results in dissolution/precipitation of certain mineral phases in hardened cement paste is key concern in performance assessment of these structures. As opposed to the existing approaches focusing mostly on microstructural changes occurring during hydration of concrete, here an approach based on Lattice Boltzmann method is proposed to model the evolution of microstructure of hardened cement paste under geochemical interaction with aggressive pore water. Lattice Boltzmann method is used to solve multicomponent mass transport in complex pore geometry. This mass transport solver is further coupled with PHREEQC to solve geochemical reactions through operator-splitting approach which enables the applicability of developed approach to varieties of geochemical systems such as one of cement paste. Further geometry update rules are defined to model dissolution/precipitation of solid mineral phases. Finally, some benchmarks are shown to demonstrate working of developed approach. The developed model can be used to evaluate changes in HCP microstructure under the influence of aggressive pore water resulting in carbonation or calcium leaching.