The effect of w/c ratio and aggregate volume fraction on chloride penetration in non-saturated concrete

The diffusion of moisture and chloride in non-saturated concrete is considered as two coupled transport processes. Two coupling terms are added in the governing equations based on Fick's first law to represent the interaction between the moisture and chloride during the transport processes. The first coupling term is for the effect of moisture movement on chloride transfer, and the other is for the effect of chloride transfer on moisture movement. In this paper, an experimental study was conducted to investigate the effect of the variation of the water-cement ratio and the aggregate volume fraction on the coupling parameter associated with the first coupling term (DCl-H). To this end, a chloride ponding test was designed and performed on two sets of fully and partially saturated concrete samples made with different water-cement ratios and aggregate volume fractions. The coupling parameter was determined based on the obtained test data. The results indicate that the coupling parameter DCl-H is strongly dependent on the concentration of chloride ions, water to cement ratio, and volume fraction of aggregate. A material model for the coupling parameter was developed using the experimental results.