Application of ground-penetrating radar technique to evaluate the waterfront location in hardened concrete

Abstract

The long-term performance of concrete structures is directly tied to two factors: concrete durability and strength. When assessing the durability of concrete structures, the study of the water penetration is paramount, because almost all reactions like corrosion, alkali-silica, sulfate, etc., which produce their deterioration, require the presence of water. Ground-penetrating radar (GPR) has shown to be very sensitive to water variations. On this basis, the objective of this experimental study is, firstly, to analyze the correlation between the water penetration depth in concrete samples and the GPR wave parameters. To do this, the samples were immersed into water for different time intervals and the wave parameters were obtained from signals registered when the antenna was placed on the immersed surface of the samples. Secondly, a procedure has been developed to be able to determine, from those signals, the reliability in the detection and location of waterfront depths. The results have revealed that GPR may have an enormous potential in this field, because excellent agreements were found between the correlated variables. In addition, when comparing the waterfront depths calculated from GPR measurements and those visually registered after breaking the samples, we observed that they totally agreed when the waterfront was more than 4 cm depth.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…The wall has a relative dielectric permittivity equal to ε b and an electrical conductivity equal to σ b . All media are supposed to be non-magnetic (Soldovieri et al, 2007a).…”

“…The code discretizes Maxwell equations in space and time by means of the finite-difference time-domain (FDTD) method based on Yee's algorithm. The antennas are modeled as electric line sources assumed invariant along the y axis (Soldovieri et al, 2007a). The perfectly matched layers (PMLs) are used to terminate the computational domain in order to prevent spurious reflections of the electromagnetic waves from the outer boundaries.…”

“…Accordingly, the scattering phenomenon is governed by the linear integral Eq. (20) (Leone and Soldovieri, 2003;Persico et al, 2005;Soldovieri et al, 2007a).…”

“…Specifically, the singular system {σ n , u n , v n } is introduced, with {σ n } being the sequence of singular values sorted in decreasing order, {u n } being the basis function in the unknown space and {v n } being the basis functions in the data space. The regularization of the solution is achieved by means of the truncated SVD (TSVD) algorithm (Leone and Soldovieri, 2003;Persico et al, 2005;Soldovieri et al, 2007a).…”

A joint thermal and electromagnetic diagnostics approach for the inspection of thick walls

“…As is well known, GPR imaging has proved to be useful in several application fields, e.g., the detection of buried pipes, land mines, defects in structures like bridges or roads and the investigation of archaeological sites (Persico, 2014;Persico and Soldovieri, 2006;Matera et al, 2016;Rodríguez-Abad et al, 2016).…”