2011 Volume 67 Issue 3 Pages 462-473
Electrical conductivities of hardened cement pastes with and without mineral admixtures were investigated in relation to characteristics of coarse capillary pore spatial structure, which was revealed by SEMBSE image analysis technique. The pore structure was quantitatively evaluated by some parameters derived from the spatial statistical functions. There exists a good correlation between the coarse capillary pore structures and the electrical conductivity. The coarse capillary porosity and its spatial correlation distances do not contradict the total capillary porosity and pore connectedness which is induced from the FKG inequality. It is suggested that connectedness of invisible fine pores is also an increasing function of the fine porosity. In spite of the incorporation of mineral admixtures, the electrical conductivity of the pastes with the admixtures could be expressed with the same liner regression lines as the plain cement pastes without the admixtures. Furthermore, the incorporation of fly ash and silica fume did not decrease the continuity of coarse capillary pores. Nevertheless, the electrical conductivity decreased in the cement pastes with those admixtures. This fact suggests that more disconnected networks of fine capillary pores were generated in the cement pastes containing the mineral admixtures even if the total porosity was the same as the plain system without them.