A new technique for the measurement of the electrical resistivity of concrete

Abstract

The measurement of electrical resistivity is quite important in the study of concrete properties, since it provides information on permeability and hence the durability and strength. In addition, the rate of transport of aggressive ions like chlorides and sulphates, which lead to corrosion of the reinforcing steel, is controlled by permeability. In this Paper a simple and elegant technique for measuring the electrical resistivity of concrete is described. The method consists in the application of a current pulse to the steel–concrete system immersed in an electrolyte, and measuring the amplitude of the potential step, either using an oscilloscope or a digital voltmeter through an interface circuit. Using this technique the variation of the resistivity of concrete has been measured as a function of the curing time. The resulting curve has been found to follow a hyperbolic expression; this is correlated with the curve of the variation of compressive strength with time.