Simulation of Ultrasonic Response to Early Corrosion in Reinforced Concrete

Abstract

Corrosion of steel reinforcement is a major cause of deterioration in reinforced concrete (RC) structures. It often starts at the steel–concrete interface and progresses silently, without any visible signs of damage, until significant deterioration has occurred. Early detection is therefore crucial to enable timely maintenance and extend service life. This study investigates the feasibility of using ultrasonic techniques to detect early-stage corrosion in RC through finite element (FE) simulations. A two-dimensional model was developed in COMSOL Multiphysics, with a steel rebar embedded within a concrete block. Early corrosion was represented as a thin annular layer with reduced stiffness and density surrounding the steel bar, and three cases were simulated: intact steel, 1 mm corrosion layer, and 2 mm corrosion layer. The simulation results showed that thicker corrosion led to reductions in wave amplitude, delays in arrival time, and distortion of the waveform, which indicates changes in acoustic impedance and scattering at the degraded interface. These findings demonstrate the potential of ultrasonic-based methods for detecting corrosion at its earliest stages and provide a foundation for developing more sensitive structural health monitoring techniques for RC infrastructure.