Evaluation of crack repair level by measuring the electrical resistance of the crack and repair area

Abstract

Evaluation of the crack repair level (CRL) is crucial for restoring the mechanical performance of damaged concrete. Current methods rely on surface inspection or complex procedures, making reliable real-time assessment difficult. This study proposes an innovative method for estimating CRL using the electrical resistance of the crack and repair area. When a repair material containing conductive fillers is injected, current flow is restored, and electrical resistance decreases. The CRL is then inferred from the change in electrical resistance relative to the injected volume fraction. Electrical field analysis produced piecewise linear equations linking electrical resistance to CRL. Experiments conducted under varying temperature and relative humidity (RH) conditions verified the method’s accuracy. For a 40 mm crack, electrical resistance decreased from 1.38 to 0.59 kΩ as the CRL increased from 0 % to 100 % at 25 ℃ and 60 % RH. Analytical and experimental results differed by only 1–4 %, with determination coefficients greater than 0.995. This method provides a rapid and accurate tool for real-time evaluation of crack repairs, aiding structural maintenance.