Application of Air‐Coupled Sensors to Surface Wave NDT in Concrete

This paper reviews the progress of air‐coupled surface wave sensing methods in NDT of concrete structures. The theoretical background of air‐coupled sensing and its applications to surface wave measurement are discussed. The theoretical analysis shows that air‐coupled sensors are able to detect leaky surface waves that are excited by a transient point load in concrete. The air‐coupled sensing technique can be used to measure surface wave dispersion curves with SASW and MASW approaches, and to image defects in a concrete slab by measuring surface wave transmission ratio. Experimental results show that air‐coupled sensors are able to replace contact sensors in traditional surface wave tests, and therefore greatly improve test efficiency.