Controlled horizontal and vertical cutoff of reinforced concrete structures by means of electric discharge impulses

For the efficient and controlled partial removal and renovation of old concrete structures, we have been developing several electric discharge impulses (EDI)-based techniques that guide three-dimensional wave interaction and ensuing dynamic fracture development precisely as desired. Here, by performing additional series of field experiments and corresponding finite difference numerical calculations, we show the mechanical “virtual interface” effect of reinforcing steel bars (rebars) on dynamic fracture development in reinforced concrete (RC) structures. If reinforced, the depth of overall fracture generated by EDI-induced waves may become relatively shallow and only the region sandwiched by an outer free surface and a virtual interface that is formed by the nearest rebars can be “sliced” or cut off, and the rebars, which are hard obstacles for later renovation work, can be exposed. In addition to the recently reported horizontal cutoff along a horizontal virtual interface formed by the topmost rebars, we show that if the relative positions of the EDI sources, free surfaces and rebars are rightly considered, the foremost rebars can function as a vertical virtual interface in a RC block, and the block can be vertically cut off along this vertical virtual interface and only the foremost rebars can be exposed efficiently.