Improved Rayleigh wave velocity measurement for nonestructive early-age concrete monitoring

A modified one-sided technique is proposed for Rayleigh wave (R-wave) velocity measurement in concrete. Wave scattering from material heterogeneity and near-field effects may disrupt sensed R-wave signals in concrete, which is manifested as signal dispersion. Conventional one-sided measurement techniques for concrete do not consider dispersion of R-waves. In this study, the maximum energy arrival concept is adopted to determine the wave velocity by employing continuous wavelet transform. Experimental and numerical studies are performed to show the effectiveness of the proposed method. The method is applied to monitor the strength development of early-age concrete exposed to various curing conditions. Results reveal that the proposed method can be effectively used to measure the R-wave velocity in concrete structures and further to monitor the development of compressive strength in early-age concrete, regardless of the concrete moist curing condition.