Title:
Determining the Depth of Surface-Opening Cracks using Impact-Generated Stress Waves and Time-of-Flight Techniques
Author(s):
Mary Sansalone, Jiunn-Ming Lin, and William B. Streett
Publication:
Materials Journal
Volume:
95
Issue:
2
Appears on pages(s):
168-177
Keywords:
concrete; crack depth; diffraction; impact; nondestructive testing;
stress waves; time-of-flight measurements; wave speed;
DOI:
10.14359/362
Date:
3/1/1998
Abstract:
Recent research on the use of the impact-echo method for nondestructively determining the thickness of slabs and pavements has led to the development of a technique and instrumentation for determining the wave speed in concrete using impact-generated stress waves. This method is independent of the geometry of the structure, and uses time-of-flight measurements for determining the depth of vertical, inclined, curved and air- or water-filled surface-opening cracks in concrete. Knowledge of the dilatational (P-) wave speed is obtained independently from accurate travel time measurements of the P-wave along the surface of the concrete. This paper discusses the theory and equations which form the basis for the method. Numerical and laboratory results are presented to demonstrate the feasibility of the method. Experimental results are obtained using the same instrumentation (impactors, broadband transducer, and data-acquisition hardware and software) that is used in wave speed measurements and in impact-echo testing.