Numerical and experimental analysis of the effect of multi-ion electrical coupling on the sulfate convection zone in hydraulic concrete

Abstract

This study centers on investigating the effects of multi-ion electrical coupling on sulfate profiles in the convection zone of hydraulic concrete under drying-wetting cycles. Considering the moisture ingress triggered by capillary negative pressure and electrical potential gradients generated due to the varying speeds of the charged solutes, a coupled numerical model framework for moisture and multi-component ions transport is established. The influence of drying and rewetting conditioning regimes, electrochemical coupling between multi-species ions, sulfate adsorption-binding mechanism, fly ash replacement and porosity of concrete on moisture and multi-ion transport behavior is numerically analyzed. Our findings reveal that more than 60 % of the sulfate ions that penetrate the concrete matrix engage in chemical reactions. After 30 cycles, the sulfate ion content differs by approximately 21 % depending on the presence of the electrical coupling effect. Moreover, the electrostatic potential in the pore solution fluctuates sharply in the ion-rich area near the concrete surface, interacting with ion distribution in the convection zone. The knowledge gleaned from this investigation offers a robust framework for the design of concrete structures that need to withstand challenging aqueous environmental conditions marked by multi-component ions and cyclic drying-wetting processes.