Time-varying relationship between pore structures and chloride diffusivity of concrete under the simulated tidal environment

Abstract

Based on an exposure test of concrete with admixtures under a simulated tidal environment, the free chloride ion concentrations at different exposure times were measured, the apparent chloride diffusion coefficients of test concrete were fitted with Fick’s second law, and the pore structural parameters of concrete at the same time were measured by mercury intrusion porosimetry (MIP). Based on the measured results, the time-varying characteristics of porosity and pore size distribution of test concrete have been analyzed, and the time-varying relationship between the proportion of different pore diameters as well as porosity and apparent chloride diffusion coefficients of concrete have been investigated. Results indicate that, under the simulated tidal environment, the total porosity and apparent chloride diffusion coefficient of test concrete have obvious time-variation, an obvious correlation between porosity and apparent chloride diffusion coefficient can be observed, i.e. both of them decrease with time. It has been found that the time-varying proportion of various pore diameters in concrete is different. Moreover, the correlation coefficients between contribution porosities of different pore diameters and apparent chloride diffusion coefficients show an increasing trend with exposure time.