Effect of moisture content on concrete resistivity measurement

The resistivity of concrete was investigated in this study by employing the Wenner technique. Cylindrical specimens with various water/cement ratios (w/c=0.45, 0.55, and 0.65) were cast and tested. In order to study the effect of moisture content on concrete resistivity, the resistivity and weight were measured for air‐dried specimens and oven‐dried specimens. Test results show that the resistivity decreases with an increase in w/c ratio, but for the saturated concrete specimens with high w/c ratios (w/c>0.55) the resistivity difference is small. For specimens after 8‐hours of air drying, the water loss ratio was about 0.7% and the normalized resistivity increased from 5% to 10% in comparison with the saturated concrete specimens. When the water loss ratio was higher than 3%, the concrete resistivity abruptly increased for all mixes. Therefore, the effect of moisture content on concrete resistivity measurement should be considered in durability evaluation.