科研之友
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摘要
A slice sample is cut and saturated with 10% concentration sodium chloride solution. The saturated slice sample and 10% concentration sodium chloride solution are then connected in a continuous ring mould as a secondary coil in a non-contact electrical resistivity apparatus. The chloride diffusion coefficient D-Cl of hardened paste and concrete is calculated from the measured electrical resistivity of the slice sample based on the Nernst-Einstein equation. There is a bilinear relationship between the chloride diffusion coefficient and the reciprocal of time logarithm for different hydration periods of the samples. The slope is higher before 72 h than after 72 h. Parameter K-D is obtained to describe connectivity for migration of ions. There is a good linear correlation of the chloride diffusion coefficient between concrete with an aggregate volume fraction 65% and paste with the same water-cement ratio, showing that the chloride diffusion coefficient of a concrete is a function of the chloride diffusion coefficient of a paste with the same water-cement ratio and the paste matrix volume fraction (1 - V-a) inside the concrete.
