Evaluation of Concrete Permeability by Monitoring Alkali Saturated Conductivity of Concrete Incorporating Mineral Admixtures

Abstract

Concrete conductivity is the reflection of the micro pore structure and the pore solution conductivity of concrete, but the conductivity of pore solution changes considerably as different mineral admixtures are added, though the change is not always relevant to permeability and Cl- diffusivity. Saturation of concrete capillary pore system with 1 mol/l KOH solution through vacuum processing was tempted to maintain the pore solution conductivity constant, after which the concrete conductivity was a reflection of concrete porosity and tortuousity that closely related to Cl- diffusivity. Charge passed of concrete was also measured for comparison. It is shown that the conductivity of alkali saturated concrete without mineral admixtures was the biggest, followed by the concrete with natural zeolite（20％）, fly ash（30％）, slag（40％）metakaolin 20% and 10% of silica fume.