Investigating resistivity testing as a method for quality control of concrete mixtures

Concrete is a composite material. It is a mixture of cement, sand, rocks and water. It is the second largest consumable product in the world. Unfortunately, many of the concrete structures before completing the designed service life experience premature deterioration and failure. In-service, the foreign components in the form of fluids (e.g., chlorides or sulfates) or gas (e.g., carbon dioxide) ingress into the porous cementitious matrix causing various durability issues and corrosion of rebar in cases of reinforced concrete. The electrical resistivity is a rapid and low-cost method to evaluate the ionic movement in concrete. The surface resistivity method is becoming popular as a quality control test to determine the durability issues due to the movement of chloride or sulfate ions, and as a corrosion indicator. In this study, the important, influential parameters that effects the surface resistivity measurements were investigated to verify and add to the research completed in the past, which includes the effect of curing method and temperature, ambient temperature, w/cm, fly ash content and sources, paste fraction, and aggregate type and size. Also, the comparative study was completed to determine the relationship of surface resistivity with transport mechanisms such as sorptivity, total absorption, and compressive strength with the change in influential parameters explained above. Furthermore, a comparative study was conducted on statistical techniques, multiple regression, decision tree, and neural networks to define a simple and best suitable model to predict resistivity and to develop a quality control criteria to determine the important concrete mixture parameters, w/cm and fly ash content, but this study didn't fulfill the desired goal of the study. Another study was performed by using statistical analysis, Levene's test, ANOVA, Welch's test and Tukey's test to develop a quality control method which successfully determines the presence of fly ash content and potential w/cm of the concrete mixture. The efficacy of statistical criteria was evaluated with various concrete mixtures with similar and different material sources. The development of novel quality control criterion to verify the key concrete mixture parameters, w/cm and fly ash content would help to minimize the durability issues, repair and rehabilitation cost, and an increase in service life of the concrete structure