Dielectric and electrical properties of ordinary Portland cement and slag cement in the early hydration period

The dielectric constant and electrical conductivity of ordinary Portland cement (OPC) with water-cement ratios (w/c) of 0.30, 0.35 and 0.40 were measured for the first 30 h hydration, using a microwave technique (frequency range 8.2-12.4 GHz). It was found that both the dielectric constant and electrical conductivity of the cement paste are sensitive to w/c. It was also found that the higher the frequency the greater the electrical conductivity but the smaller the dielectric constant. The dielectric constant and electrical conductivity of high- and low-slag cement with water-solid ratio (w/s) of 0.40 were also measured in the first 30 h after mixing. The relationship between the dielectric and electrical properties of cement paste and cement hydration are discussed. 36 refs.