Inspection of Insulated Concrete Form walls with Ground Penetrating Radar

Insulated Concrete Form (ICF) walls are widely used for a full range of building designs including residential, theaters, schools, and hospitals. ICF manufacturers cite several advantages compared to traditional building materials but builders are concerned by honeycombing that may occur during the pouring of the concrete, where gaps are left in the concrete. The development of gaps generally occurs between the foam and the surface of the concrete. Acoustic sounding, a traditional inspection technique to locate voids, would be unsuccessful due to the plastic foam. In this research study, Ground Penetrating Radar (GPR) was proved successful in detecting gaps that developed between the foam and the concrete, voids intentionally created in the concrete, and voids that developed during the pouring operation. Small voids (e.g., less than ¾ in.) were difficult to detect but are not likely to cause any hazard to the structural integrity of buildings. The tests were performed at different stages of concrete curing using both the 1500 MHz and the 2600 MHz antennas. It is shown in this paper that the first void in the concrete was detected at day 7. However the best results were achieved at day 28 of curing. Data analysis has shown the success of the 1500 MHz antenna, but also the limits of the 2600 MHz antenna in the detection of buried voids in ICF structures.