Seasonal Variation and Age-related Changes in the Relative Permittivity of Concrete Bridge Decks on Korea Expressways

Abstract

The purposes of this study were to investigate the seasonal variations in the relative permittivity of actual concrete bridge decks of various ages on Korea expressways, and to propose a practical way to calibrate two critical effects, to assess the condition of the concrete bridge decks with better accuracy. For these purposes, fifty-three actual concrete bridge decks on Korea expressways were scanned using an air-coupled ground penetrating radar (GPR) system, and the relative permittivity of the concrete was evaluated from the GPR data in the field. A statistical analysis showed that the relative permittivity of the concrete bridge decks in Korea are closely correlated with seasonal changes and concrete ages. For concrete bridge decks aged 10 years or older, the effect of concrete age was not as significant as that of relative humidity of the air on relative permittivity of concrete. Based on the results, a simple calibration process was proposed to suppress the effects of seasonal variation and age of concrete on the measured relative permittivity of the concrete decks on actual bridges. As will be discussed, the resulting relative permittivity method produced better agreement with the current condition of the concrete bridge decks as determined by visual inspection and other complementary methods (energy attenuation of GPR signals and corrosion potential measurements) than without the calibration process.

A Practical Approach to Condition Assessment of Asphalt-Covered Concrete Bridge Decks on Korean Expressways by Dielectric Constant Measurements Using Air-Coupled GPR

“…In other words, as the age increased, the dielectric constant decreased at a reduced rate. This trend followed the behavior observed in the equation for bare concrete bridge deck [20]. In this study, an approximate formula representing the relationship between the dielectric constant of concrete deck with asphalt overlay and concrete age (service period of bridges) was established using nonlinear regression analysis, ε Age r,c = −1.08 ln(Age conc ) + 11.41 (8) where Age conc is the concrete age at the time of GPR measurements (year).…”

“…In general, the GPR survey data appears to be greatly dispersed, which is mainly due to the variability of bridge components (e.g., concrete age, degree of deterioration, water content, etc.). However, it could be observed that the higher values of relative permittivity are shown in relatively new concrete bridges (0-10 years), which was also observed in concrete bridge decks without asphalt overlay [20]. Young concrete has plenty of water in the concrete pore system, leading to higher dielectric constant than the values in mature concrete in old bridges.…”

“…The change of atmospheric relative humidity of 10% results in the change of dielectric constant of top concrete inside the pavement of about 0.11. The ratio of change is only 12% of the case of the bare concrete bridge decks in Korean expressways [20]. Furthermore, the influence of the variation of RH on the dielectric constant of concrete is less than 1% of the variation of ln (Age ).…”

“…However, most experimental data were obtained in the laboratory and did not effectively consider the actual field effects, such as seasonal variations and age-related changes over the long-term. Recently, Rhee et al [20] investigated the effect of some influencing parameters (concrete ages and variations of relative humidity of air) on the relative permittivity of concrete decks in actual bridges on Korean expressways with ages from dozens of days to 27 years. The study was only focused on bare concrete decks with limited numbers of bridges (53 bridges on Korean expressways).…”

Reflectivity-Consistent Sparse Blind Deconvolution for Denoising and Calibration of Multichannel GPR Volume Images

“…Using the sparse and smooth reflectivity R obtained from the above iterative process, the transmitted wavelet W can be estimated based on (9). This is done in a similar way to the derivation of the Wiener filter.…”