Electrical conductivity of Portland cement mortars

Mortars containing volume fractions of aggregate less than 0.35 were prepared at w c = 0.35, 0.40, and 0.45 and hydrated for 1, 14, and 28 days. Mortar electrical conductivities were determined by impedance spectroscopy, and the experimental data were fitted to the polynomial, where, σ m is the mortar σ m = A + B V a V m + C V a V m 2 + D V a V m 3 conductivity, V a is the aggregate volume, V m is the mortar volume, and A, B, C, and D are constants. Mortar electrical conductivity behavior appears to involve a competition between the insulating aggregate which lowers the mortar electrical conductivity and the development of a transition zone between the paste and aggregate which increases the conductivity. Values for the transition zone electrical conductivity were determined.