Air-coupled impact-echo delamination detection in concrete using spheres of ice for excitation

The aims of this paper are to demonstrate that ice can be used as a suitable impactor to excite the acoustic modes in concrete associated with delaminations and to compare ice sphere impacts with traditional steel ball impacts. Simultaneous acoustic recordings and high-speed photography of representative low-velocity impacts with parametric analysis compare impact characteristics of steel balls and ice spheres on intact and delaminated concrete. These results agree qualitatively with Hertzian contact theory for low-velocity impacts. Excitation of concrete using continuous impacts of ice spheres of multiple sizes and a frequency analysis allows the acoustic signature of delaminations to be classified. The use of ice as an impactor for excitation of acoustic modes in concrete is thus demonstrated. © 2013 Springer Science+Business Media New York.