Crack depth estimation of concrete structures by electrical resistance measurements of crack areas

Abstract

This study proposes a new method to investigate crack depth (D) by measuring the electrical resistance of crack area. The crack depth was estimated using the difference in electrical resistance (ΔR) across the crack area based on the inner electrode spacing. Based on the results of electrical field analysis, the correlations between ΔR and D were proposed as piecewise linear equations. This relationship was experimentally validated under various temperature and relative humidity conditions. The proposed method was applied to concrete cracks at the Dong Chun Bridge in Daegu, Korea, and the estimated crack depth was 75.34 mm. This result showed a 7.78 % error compared with the crack depth measured by a commercial ultrasonic sensor (81.7 mm), thereby validating the proposed method. This simple and reliable technique can effectively support on-site inspections and enhance the accuracy and efficiency of crack assessment in real concrete structures.