The Chloride Permeability Test Method (RCPT) - American Society of Testing and Materials (ASTM) C1202 or the T277 Test Method of the American Association of State Highway and Transportation Authorities (AASHTO), is practically a measure of The electrical conductivity of the concrete, which depends on both the pore structure characteristics and the porous concrete chemistry of the concrete. This paper discusses the effects of several factors, such as cement composition, cement substitution by supplementary cementing materials and the inclusion of aggregates, on electrical conductivity or the RCPT results of cement and concrete mortar. Analyzes based on published results have indicated that all three factors can have significant effects on the chemistry and specific conductivity of the concrete pore solution, which has little to do with ion transport in the solution. Therefore, RCPT is not a valid test for the evaluation of the permeability of concrete made with different materials or different proportions.