Real-time evolution of electrical resistance in cracking concrete

The aim of this paper is to present a real-time relation between the evolution of the electrical resistance and the crack width opening in a saturated concrete sample. The splitting (Brazilian) test has been enhanced and adapted so that the monitoring of a single crack opening and the electrical resistance of the specimen are possible. The experimental results showed that the electrical resistance is constant before the peak (when no crack is observed) and decreases only when the peak of load is reached and when a crack is initiated. No threshold value and no delay between the crack opening and the resistance evolution have been observed, even in the case of a breathing crack. The evolution of the electrical conductance has then been modeled by taking into account the (simplified) morphology of the crack and assuming a constant value for the electrolyte conductivity. The model and the experimental conductance through a traversing crack have proved to be in good agreement. (C) 2009 Elsevier Ltd. All rights reserved.