Insulated Concrete form Void Detection Using Ground Penetrating Radar

Insulated concrete form (ICF) construction consists of interlocking polystyrene forms and poured-in-place concrete. The forms are left in place after the concrete is poured to form an efficient insulation barrier. Consequently, it is difficult to ascertain the presence of flaws in the concrete, such as voids at the boundary between the form and the concrete, using traditional inspection methods without removing, and thus damaging the polystyrene forms. In a research investigation, it was found that ground penetrating radar (GPR) utilizing a 1.6 GHz center-frequency antenna is useful for locating voids at the concrete-form boundary and voids buried in the concrete The highest quality data were obtained from vertical profile lines. The detection of the voids was possible by performing a background-removal process to the data that stripped the direct-coupling between the transmit and receive antennas, which effectively isolated the concrete surface reflection. Mapping the change in arrival time and amplitude of the concrete surface reflection was useful in characterizing, to some extent, the dimensions and depths of the voids. The detection of voids buried 2.5 to 10.8 cm (1.0 to 4.3 in.) in the concrete was also achieved after 3 days of curing. Additional data processing was required to enhance the detectability of the buried voids. The generation of a 3-D dataset and subsequently viewing thin depth slices of data was useful in distinguishing the void reflections from the reinforcing reflections.