Frequency-dependent dispersion of high-frequency ground penetrating radar wave in concrete

This paper studies the dielectric dispersion of high frequency radar wave in concrete in early-aged and hardened concrete specimens. Frequency-dependent spectra of phase velocity nu(omega) were measured to deduce the spectra of real part of dielectric permittivity epsilon'(omega). The dispersion was measured by three high nominal ground penetrating radar frequencies (1.5, 1.6 and 2.6 GHz), experimenting on two steel bars with concrete cover 50 and 100 mm. It was found that nu(omega) and epsilon'(omega) dispersed at lower frequency, but became stable at high frequency regions, which agrees with the classical GPR plateau. The same frequency components at different nominal antenna frequencies show a close range of v(w) and epsilon'(omega) in concrete of different ages. The results in this paper warrant further investigation of using GPR wave to study material properties. (C) 2011 Elsevier Ltd. All rights reserved.