Surface-Wave Based Model for Estimation of Discontinuity Depth in Concrete

Abstract

In this paper, we propose an accurate and practical model for the estimation of surface-breaking discontinuity (i.e., crack) depth in concrete through quantitative characterization of surface-wave transmission across the discontinuity. The effects of three different mixture types (mortar, normal strength concrete, and high strength concrete) and four different simulated crack depths on surface-wave transmission were examined through experiments carried out on lab-scale concrete specimens. The crack depth estimation model is based on a surface-wave spectral energy approach that is capable of taking into account a wide range of wave frequencies. The accuracy of the proposed crack depth estimation model is validated by root mean square error analysis of data from repeated spectral energy transmission ratio measurements for each specimen.

Applicability of Diffuse Ultrasound to Evaluation of the Water Permeability and Chloride Ion Penetrability of Cracked Concrete

“…Most previous ultrasonic non-destructive assessment techniques for concrete structures have been developed through the use of low frequency excitations, typically below 50 kHz. The reason for using the aforementioned low-frequency range is to minimize wave scattering by employing long wavelength components compared to the sizes of heterogeneities (e.g., pores, cracks, fine and coarse aggregates) in concrete [9]. In contrast, when the wavelength of ultrasound is much smaller than such heterogeneities (i.e., high-frequency ultrasound above approximately 200 kHz), coherent parts quickly dissipate and incoherent parts multiply scatter in the medium, which is considered as diffusion phenomena of ultrasound, as illustrated in Figure 1.…”

“…Ultrasonic wave velocity [7], transmission of surface waves [8,9], diffusion of high-frequency waves [10,11,12,13,14,15,16], coda wave interferometry [16,17,18], characteristics of guided waves [19], and nonlinear characteristics of ultrasound [20] have been studied for application to the nondestructive evaluation of defects in concrete. Each ultrasonic test method is based on a unique theoretical concept, and has distinct advantages and disadvantages for different applications [5,21].…”

Monitoring of self-healing in concrete with micro-capsules using a combination of air-coupled surface wave and computer-vision techniques

“…Among various coherent wave methods, the surfacewave transmission is the most sensitive to change in crack depth 29,[31][32][33][34][35][36] or crack repairing, 37 as most of the energy is concentrated, within the depth of wavelength, around the impact surface. 38 Therefore, many studies have investigated the correlation between crack depth and surface-wave parameters.…”

“…38 Therefore, many studies have investigated the correlation between crack depth and surface-wave parameters. [32][33][34][35] To improve the applicability of surface-wave techniques, fully contact, [31][32][33] partially aircoupled, 34,36,39 and fully air-coupled configurations 35 have been developed over the last two decades. The sensitive characteristics of surface-wave transmission across different cracks have the potential to be used to monitor the selfhealing/sealing progress of concrete (e.g., decrease of crack depth due to crack sealing from a crack tip or increase of crack bridging at intermediate locations).…”

Rayleigh Wave Calibration of Acoustic Emission Sensors and Ultrasonic Transducers

“…For thin structural elements, Lamb (or plate) waves are important, while Rayleigh (or surface) waves provide the means to interrogate medium to heavy walled structures for locating and evaluating near-surface defects. Recent developments [12,13,14,15] using guided waves for various inspection goals provided expanded avenues for deployment. For basic test methods with different wave modes, see standard textbooks for UT and nondestructive evaluation and references [1,2,3].…”