Quantitative Relationship between Chloride Penetration Depth and Hydraulic Conductivity of Concrete under Hydrostatic Pressure

Hydraulic conductivity is a key parameter in the penetration of harmful substances, and therefore it is important to better understand microstructure-based durability performance in cementitious materials. The hydraulic conductivity of cementitious materials has typically been obtained by measuring the amount of water entry based on Darcy's law. However, such measurement is challenging, and it is difficult to study penetration behavior along the longitudinal section of cementitious materials. In this work, a new experimental method was designed to measure the chloride penetration depth of cementitious materials and enable visual examination of hydraulic behavior in the longitudinal section of materials under a hydrostatic pressure gradient. The chloride penetration depth can be converted into hydraulic conductivity if the hydrostatic pressure applied to the materials, the chloride penetration depth, and the chloride concentration at the depth are known. As part of this work, the effect of capillary porewater on the hydraulic conductivity was examined. The result was compared with experimental data, and revealed that seawater penetrates into concrete and is mixed with capillary porewater and diluted, and the mixed water again penetrates into the concrete by hydraulic pressure.