Characterization of surface crack depth and repair evaluation using Rayleigh waves

The 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.