Electrical resistivity of Concrete Mixtures Containing a High Volume of Pozzolanic Materials

In this study, 19 different mixtures, including 11 air-entrained mixtures, three flowable mortar mixtures, and five self-consolidating concrete mixtures were fabricated to investigate the effect of different factors, including air content, type and composition of pozzolans, and water to binder ratio(w/b) on electrical resistivity. These mixtures were made by substituting between 30-60% of cement weight by pozzolanic materials with 0.28 to 0.34 w/b ratios. The pozzolanic materials included zeolite, pumice, wollastonite, and slag. Electrical Surface and bulk resistivity tests were performed at different ages on 100 mm x 200 mm cylindrical specimens, and the relationship between the test results was investigated. The results of the study indicated that the electrical resistivity is related to the water to binder ratio, type and composition of pozzolans used, replacement level of pozzolanic materials, and entrained air amount. Among these factors, the w/b ratio and the replacement level of pozzolan used had a greater effect on the electrical resistivity of concrete. The combination of slag and zeolite had the greatest effect, and the combination of slag and wollastonite had the least effect on the development of electrical resistivity results in the mixtures. The result of regression analysis showed that there is a strong correlation between the results of bulk and surface resistivity of concrete at different ages.