Evaluation of Concrete Bulk Resistivity as the Key Performance Index for Chloride Transport in Concrete and Rate of Hydration

In the last decades, various test methods have been developed to evaluate the resistance of concrete against chloride penetration. This study investigated twelve types of concrete to determine which test method is reliable for ranking concretes. The concrete evaluation included different water to binder ratios (w/b) of 0.4, 0.45, and 0.50 with and without supplementary cementitious materials (SCMs), zeolite, and silica fume. The test methods used included the rapid chloride permeability test (RCPT), rapid chloride migration test (RCMT), salt ponding test (chloride profile), and bulk electrical resistivity. The test results revealed that all test methods are appropriate for diagnosing chloride penetration resistance grading of concrete and can be used as a performance indicator. This result indicates a proper correlation between the results of the tests. The finding showed that the limitation on the w/b ratio is inadequate to ensure high chloride penetration resistance, and the lowest chloride penetration was recorded for concrete with binary SCMs zeolite and silica fume. Results revealed that the increase in concrete electrical resistivity due to the replacement of pozzolans is much more significant than the w/b ratio effect. Also, it was found that electrical resistance is a function of pore structure and chemical composition of concrete pores, which is used as a performance index to save testing time and cost effectiveness.