multiVIEW conducted surveys for undocumented and non-visible repair zones on Highway 401 near Toronto, Ontario. Historical records of repair did not exist or were hard to locate.
Methodology – identifying historical repair zones
Data were acquired at 10mm station intervals. Depths were determined from the localized point scattering diffractions and validated against subsequent core sampling. The GPR survey revealed many past repairs and structural issues which were neither on record nor visible from the surface.
Figure 1 shows surface cracks observed at fiducials 16 and 17 (F16 and F17) during GPR data collection. A previous repair and tilting of the concrete slab to the left of the repair are also visible. The surface cracks bracket the repair.
Figure 2 shows a different repair character. In the repaired section, the steel reinforcing (and possibly the concrete slab) have been removed.