Comprehensive Condition Assessment of Dam Crest Structures Using Multi-Method Non-Destructive Evaluation Techniques

This paper presents a comparative analysis of a multi-modal non-destructive testing and evaluation program in evaluating the condition of concrete elements in two dam structures in Quebec, Canada. For each dam structure, one area, exhibiting varying degrees of deterioration, were meticulously investigated to evaluate the surface and subsurface integrity of the concrete. Visual surveys revealed surface-level defects, including cracks, spalling, and evidence of previous repairs. Subsurface conditions were evaluated through a multi modal non-destructive evaluation program. Ground-Penetrating Radar (GPR) was used for rapid screening of the area for potential delamination and voids, particularly in areas with prior repairs. Ultrasonic pulse echo (UPE) was utilized to verify the findings of the GPR scans, providing high-resolution data on internal defects within the top 500 mm. In addition, Impulse-Response (IR) testing was deployed to affirm presence of potential anomalies (voids and delamination) by identifying high-mobility zones. Spectral Analysis of Surface Waves (SASW) was employed to evaluate mechanical properties, revealing variations in shear wave velocity, with lower velocities correlating to compromised material integrity. The main objective of the study was to study the effectiveness of these NDT-E methods in identifying sub-surface anomalies. The findings of this study revealed a good agreement between among between different assessment methods, enhancing confidence in defect detection and material characterization. While much of the concrete was found to be in satisfactory condition, several areas especially those with prior repairs exhibited notable surface and subsurface degradation. The findings emphasize the need for targeted maintenance and repair strategies to mitigate the identified defects and ensure the long-term safety and performance of the dams. This study showed the efficacy of combining multiple NDE techniques for detailed, non-invasive assessments of dam infrastructure.