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Voids and Honeycombing in Concrete Spillway
After experiencing significant delays during construction, voids and honeycombing were suspected between two monolithic concrete layers each 1 meter thick. A series of GPR scans were taken over the concrete slab. Images of the concrete at the interface were computed, showing suspect areas where voids were present. Subsequent coring and epoxy injection confirmed the GPR images.
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Water and Voids below Concrete Slabs
A large hole had appeared in a parking garage slab-on-grade. It was found that water springs were present below the slab. GPR was used to produce an image showing the presence and extent of water and voids below the sub-base.
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Broken Drains below Concrete Slabs
The example illustrated on the right is of a factory floor where it was suspected that a broken floor drain had washed out some of the sub-base. GPR scans and 3D imaging of the data below the slab revealed two major voided areas several inches depth and another smaller area in the main floor. A more serious gap of about one inch thickness was located below a more heavily loaded and thicker section of floor slab. The imaging map permitted recommendation of grout injection to provide support for this floor, thereby substantially reducing disruption of the factory process.
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Voids and Water below Concrete Slabs
A pedestrian tunnel walkway at a railway station was scheduled to undergo an upgrade. Severe water infiltration indicated that there was a chance of water scouring below the slab. GPR scans were obtained and 3D slices computed to evaluate the condition below the slab. It was found that there was no severe scouring and minor water infiltration, however a construction joint was defective and a trench to the elevator shaft should be carefully inspected.
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Cover to Reinforcing Steel
Due to serious localized problems with the depth of cover of reinforcing steel, our client wished to know the depth of cover over a large irregularly shaped area, covered with granite tiles. Many data scans were taken in a regular pattern. The location of the bars relative to the surface was then digitized and subsequently contoured.
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