ESTIMATING LONG-TERM DURABILITY PARAMETERS BASED ON ELECTRICAL RESISTIVITY MEASUREMENTS

Concrete’s electrical resistivity is one of the main parameters controlling the initiation and propagation of reinforcement corrosion. It is common knowledge that concrete electrical resistivity is mainly dependent on the porosity, temperature and the moisture content. This research work studies the possible relationship between concrete electrical resistivity and compressive strength of concrete. It is intended to evaluate the possibility of predicting the strength gain of concrete at a given time using the resistivity measurements. Furthermore, in order to take account of temperature effect, the variation of resistivity due to temperature is studies. Results obtained indicate that there is a strong relationship between compressive strength at a given age and the electrical resistivity. A relationship for prediction of the compressive strength using electrical resistivity of concrete is suggested that allows the estimation of the compressive strength based on the electrical resistivity value. Furthermore, it was observed that temperature has a significant influence on the electrical resistivity of concrete. Based on test results, a relationship similar to the Arrhenius equation is also suggested that can be used for prediction of electrical resistivity with temperature. It is suggested that a method, similar to the maturity method for predicting the strength gain with time and temperature, can be used successfully to account for prediction of electrical resistivity with time and temperature. Based on this method, the electrical resistivity and compressive strength of concrete at 28 days is predicted using values of electrical resistivity of up to 4 days. Errors in estimates were less than 15 %. If values of up to 7 days are used, the error associated with the estimates is less than 5 %. 1