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Construction Practice Classification


multiVIEW conducted an investigation of Highway 401 near Toronto, Ontario in order to determine construction practice classifications.

Many of the historic construction practice were not known and documentation was not readily retrievable.The objective of the RoadMap GPR survey was to classify changes in construction practice via created images and tabulated data.


Data was collected concurrently with differing frequencies and different path alignments. Multiple passes over several lanes over a distance of about 14 km identified numerous zones of past repairs and structural issues which were neither on record nor visible from the surface.


Figure 1 shows joints in a concrete slab covered by asphalt (indicated by yellow arrows).

After correlating the GPR with other data, the abrupt localized changes were confirmed to be joints in the underlying concrete slab.
The change in signal character was associated with fine grained material and water retained in the concrete joints.
Slight deformation of the asphalt structure above the joints suggested upward migration of the deformation. These characteristics were clear indicators of slab movement at the joints.