Characterization of Cement Paste in Fresh State Using Electrical Resistivity Technique

The impedance spectroscopy technique was used to monitor the electrical resistivity of various cement paste mixtures during first 2 hours after mixing before the setting time. The conductivity and pH of the pore solutions extracted from fresh cement paste mixtures was also determined. The conductivity of pore solution extracted from select hardened paste mixtures cured in sealed moisture condition was also obtained. These data were used to investigate the various influential parameters such as (1) the effect of time on the electrical resistivity, (2) the effect of supplementary cementitious materials and chemical admixtures on the electrical resistivity, (3) the effect of w/c ratio on the electrical resistivity, (4) tortuosity and the relationship between electrical resistivity of paste and pore solution and (5) correlation between the pH and electrical conductivity of pore solution. In addition, a numerical model was proposed to estimate the conductivity of pore solution in fresh state.