A coupled chemo-transport-mechanical damage model for the mineral transformation in cementitious materials under a sulfate-rich environment

Abstract

The present study proposes a coupled chemo-transport-mechanical damage model integrating thermodynamics, fluid-solid transformation, and mechanical damage modeling to predict the physicochemical characteristics of cementitious materials under a sulfate-rich environment. For verifying the proposed model, calcium sulfoaluminate (CSA) cements with various molar ratios of calcium sulfate over ye'elimite (m-values) were adopted for a case study. The thermodynamics model for the phase assemblage of CSA cements with various m-values under a sulfate-rich environment is compared with the experimental outcomes. The model parameters in the fluid-solid transformation and mechanical damage models are fitted through the available experimental data in the literature. Mineral compositions, crystallization pressure, effective elastic modulus, delayed ettringite formation, and microcracks of CSA cement pastes were modeled by a proposed coupled chemo-transport-mechanical damage model, with model parameters fitted to experimental data, thereby assessing the applicability of the proposed model. The predicted results show that an increase in m-value of the samples increases the rate of sulfate ion penetration and crystallization pressures. Moreover, DEF, microcrack evolution, and mechanical degradation can be attributed to the amount of ye'elimite and hydrated monosulfate of the samples.