Abstract

The destructive techniques that can be used to estimate the concrete quality are expensive and time consuming and are often accompanied by following reinforcing and repair. Therefore, non-destructive testing (NDT) methods have drawn the attention of some researchers. There is an increasing interest in electrical resistivity as non-destructive tests for quality control of concrete structures in the last decades. Electrical resistivity is a technique that is rapid and inexpensive. This project studied how the electrical resistivity of concrete and mortar cylinders immersed in different solutions changed with time in order to investigate various factors. In the two rounds tests of concrete and mortar specimens, it was found that the electrical resistance is highly influenced by the moisture content of the specimens, the immersion solutions, the water-cement ratio of the concrete as well as the addition of supplementary cementitious materials (SCMs). In addition, it was observed in the experiments that the electrical resistivity of the concrete specimens decreased rapidly within 24 hours after immersion in the solution (the specimens were dried in advance for 30 days), and the rate of decrease gradually slowed down over the next 27 days. It is also showed that the electrical resistivity of mortar specimens was significantly lower than the concrete with a similar mixture design. However, for the portion of the research that investigated the solution penetration with time by using internal sensors, the tests results are not adequate data to draw a conclusion.