Damage assessment of reinforced concrete retaining walls using an automated inspection system integrating impact-echo and ground-penetrating radar

This study presents the engineering development and field validation of an automated scanning platform integrating established impact-echo (IE) and ground-penetrating radar (GPR) methods for condition assessment of vehicle-accessible reinforced concrete retaining walls. It was designed for the challenges unique to vertical inspection and refined through iterative prototyping. A coordinated post-processing workflow generated delamination, energy-attenuation, surface-stiffness, and corrosion-indication maps. The system was deployed on reinforced concrete retaining walls and enabled continuous longitudinal scanning over selected 1-m-high wall regions, together with spatially coordinated multimodal inspection outputs. Three deterioration regions were examined: corrosion only, delamination only, and combined corrosion with delamination. Results were validated by ultrasonic tomography and core extraction of reinforcement, supporting the system’s ability to localize and differentiate the selected deterioration conditions within the tested retaining-wall regions. The platform therefore demonstrates feasibility for structural health monitoring of vertical infrastructure, offering reliable multi-sensor assessment to support targeted maintenance and repair.