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Problem Statement
Reinforced concrete culverts are critical components in transportation and drainage infrastructure, ensuring safe water conveyance and load transfer. Over time, these structures are subjected to traffic loading, environmental exposure, moisture ingress, chloride penetration, and material fatigue, which may lead to deterioration, corrosion of reinforcement, void formation, and loss of serviceability.
Conventional inspection methods such as visual surveys or coring are often invasive, time-consuming, and limited in scope, failing to capture the internal condition of the culvert in a holistic manner. As a result, there is a pressing need for non-destructive, high-resolution, and rapid assessment techniques that can provide actionable insights into the structural health and durability of culverts for asset management and preventive maintenance planning.
Overview
Ground Penetrating Radar (GPR) was deployed for a non-destructive evaluation (NDE) of a reinforced concrete culvert to assess its structural integrity and support preventive maintenance planning. The survey covered 144.5 m² with a high-density 10 cm grid spacing, ensuring comprehensive coverage and fine-scale resolution.
Methodology
A GPR system with a 500 MHz central frequency and 250–750 MHz bandwidth was employed to optimize the depth–resolution tradeoff required for infrastructure investigations. A total of 260 radargrams were acquired and processed using advanced 2D and 3D imaging workflows, including filtering, migration, amplitude analysis, and volumetric reconstruction.
Key Findings
The processed dataset yielded critical insights into culvert condition and performance:
Rebar Mesh Mapping: High-resolution imaging of embedded reinforcement, including rebar spacing assessments and concrete cover thickness estimation.
Interface Characterization: Clear delineation of the asphalt–concrete contact zone.
Material Degradation Mapping: Identification of localized deterioration zones, voids, and delamination features within the slab.
Corrosion Potential Zones: Detection of anomalous reflections indicative of possible moisture ingress and early-stage corrosion risks.
Structural Elements: Precise localization of abutments and supporting walls, aiding in load-bearing capacity assessment.
Engineering Impact
This investigation enabled:
Condition-Based Monitoring (CBM): Establishing baseline structural health data for future comparative studies.
Serviceability Evaluation: Verifying functionality of structural components relative to design intent.
Life-Cycle Extension Planning: Providing data-driven recommendations for targeted rehabilitation and preventive maintenance strategies.
Compliance with Standards: Workflow aligned with ASTM D6087 guidelines for GPR in concrete evaluation.
Conclusion
The study demonstrates GPR’s effectiveness as a non-invasive diagnostic tool for civil infrastructure. By integrating structural integrity assessment with quantitative deterioration mapping, the methodology enhances decision-making for long-term asset management and infrastructure resilience.
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