Speaker
Description
Reliable condition assessment of concrete structures without destructive methods remains a persistent challenge in civil engineering. The focus of this study is to examine whether a single high-frequency GPR system can combine dielectric characterization of concrete with rebar detection in structural integrity assessment. This is important because dielectric characterization provides insight into the material’s response to electromagnetic waves, while reinforcement detection supports structural evaluation. The objectives are to establish a procedure for estimating the dielectric constant of plain concrete through GPR-based virtual depth calibration and to evaluate the capability of the same system to locate and quantify steel rebars at different cover depths. Plain concrete specimens of 150 mm thickness were prepared with water-to-cement ratios of 0.45, 0.50, 0.55, and 0.60. The known thickness was compared with the virtual thickness derived from 2.3 GHz GPR responses. A time-zero correction was introduced to align measurements, enabling back-calculation of the dielectric constant. A reinforced concrete slab containing rebars of 12 mm, 16 mm, and 20 mm diameters was cast with cover depths of 25 mm, 50 mm, and 75 mm. GPR images were analyzed to identify rebar signatures and assess the influence of bar size and cover. The findings indicate that the method can capture consistent dielectric values across concrete mixes. Distinct hyperbolic patterns confirm detection of reinforcement and variation with diameter and cover. These outcomes suggest that a combined dielectric estimation and rebar detection approach is achievable with one GPR configuration, offering a pathway for integrated non-destructive testing and structural health monitoring.