The use of electrical resistivity measurement as a non-destructive test in precast concrete sleepers’ production

In the production of concrete sleepers, it is common to verify that the concrete has the necessary strength for prestress forces release by testing cylinders cured at equivalent conditions. Considering that electrical resistivity measurements may assess the pore structure evolution of concrete, this study proposes the use of this technique to estimate concrete strength evolution at factory conditions. The use of non-destructive testing methods considerably simplifies and modernizes the industrial process, leading to a reduction in labor time and waste. This paper presents a testing protocol aimed at obtaining correlation graphs between concrete compressive strength and electrical conductivity. As the temperature, size and shape of samples may be variable, this paper also presents an innovative procedure to assess correction factors. This procedure is suitable when the liquid water content is high enough not to influence the resistivity measurement. The proposed method was validated at a factory, showing a high correlation.