Reliability of electrical resistivity on the long-term monitoring of concrete

The reliability of the electrical resistivity technique in concrete was assessed. A 0.5 w/c concrete mixture was prepared and three small-scale rectangular prisms were cast. The prisms were submerged in a chloride solution for eight years, and ER measurements were taken weekly during the last five years. The results showed that the seasonal fluctuations of temperature over time and chloride ingress notably influence the ER readings. For exhaustive analysis of the ER, time-series analysis and rate-of-change approaches were used to diminish the effects of temperature and chloride penetration on the ER measurements. Significant differences, which ranged between 10% and 60%, were found between the ER values taken on the bottom and top faces of the small-scale ordinary concrete prisms. The reliability of the ER technique and time-series analysis of the data can be implemented easily for engineering works to identify heterogeneities on concrete exposed at environment changes over time.