Characterization of surface crack depth and repair evaluation using Rayleigh waves

Abstract

a b s t r a c tThe issues of surface crack depth determination and the evaluation of repair effectiveness are not trivial for concrete engineers. In the present paper, surface waves are applied on concrete blocks with artificial slots to correlate wave parameters with crack depth. To simulate crack repair with an injected material, epoxy is applied to the slots in the laboratory and quantification of the filling percentage is attempted. Simultaneously, a frequency domain boundary element method is employed for the numerical simulation of transient pulses interacting with surface breaking cracks. Experimental results compare well with the numerical ones, showing that the repair effectiveness, which so far can be evaluated only by destructive techniques, is possible by simple surface wave measurements.

Numerical simulation of Rayleigh wave interaction with surface closed cracks under external pressure

“…The variation of transmission coefficient of the linear model agrees well with the literatures[24][25][26]. The slope change was observed almost at the same time for the linear and nonlinear crack models.…”

“…When the crack depth is smaller than 0.25λ, the transmission coefficient decreases sharply; after that, the transmission coefficient decreases very slowly with the crack depth. A similar phenomenon has also been discussed in the linear interaction between a Rayleigh wave and a stress-free crack [24][25][26].…”

Dispersion of ultrasonic guided surface wave by honeycomb in early-aged concrete

“…Rayleigh wave (R-wave) is more suitable for the measurement of the near-surface properties of concrete because surface waves are guided and constrained near the surface of the material, while most energy propagates only up to a thickness equals to one wavelength [25]. The first centimeters of the concrete are within the range of R-wave propagation over a frequency range 50-200 kHz (wavelength about 10-50 mm) [29].…”

“…It can be at the pulse onset, the first negative maximum, or the maximum of the mathematical envelop in the A-scan, which makes it an arbitrary step for UPV estimation in concrete. From the material perspective, the wave propagation is governed by the level of cement hydration [10,17], aggregate grading [18], aggregate qualities and types [19,21], concrete mix proportions [21], water to cement ratio [22], and presence of cracks [23][24][25]. These variables have different values of contrasting acoustic impedance (e.g.…”

New Trends in Materials Nondestructive Characterization Using Surface Acoustic Wave Methodologies

“…However, www.intechopen.com New Trends in Materials Nondestructive Characterization Using Surface Acoustic Wave Methodologies 253 for the case of actual cracks, which were simulated by thin, flakey, light inclusions, the random orientation and general shape complicates the anticipated results and increases experimental scatter. This study aims to supply more experimental data in the area of surface waves in media with random and randomly oriented inhomogenity, which has not been studied as widely as stratified media [11,25] and media with surface breaking cracks [26][27][28][29]. The results presented herein are realistic due to the shape of the light inclusions, while size and population of inclusions leave their fingerprint on the phase velocity and attenuation curves since large population of small inclusions impose stronger attenuation that small population of larger size.…”