Left: radargram obtained along a concrete pillar. Right: interpretation
Left: GPR amplitudes reveal the microscopic structure of concrete and provide valuable information about the stress-strain field. Right: Cracked concrete slab. There is an evident match between crack location and GPR amplitudes
Three-dimensional GPR model of a reinforced concrete slab where the steel reinforcement mesh is clearly detected
Civil Engineering applications
Concrete is the most commonly used man-made material on earth. It is an important construction material used extensively in buildings, bridges, roads and dams. Its uses range from structural applications, to driveways, basements, sidewalks, curbs, pipes and drains.
Concrete structures deteriorate with time even though it is inherently a durable material. This is because the concrete’s durability, under any given set of exposure conditions, varies with the concrete mixture proportions; the presence and positioning of reinforcement; and the detailing, placing, finishing, curing, and protection it received.
Non-destructive test (NDT) methods have been developed over the years to estimate the strength and condition of concrete.
Ground penetrating radar (GPR) is the most commonly used NDT in concrete condition assessment. It can reveal a wealth of internal detail without the need for coring or breaking out. Survey results are presented as easy to understand engineering CAD plans, elevations and sections.
Small, hand-held, high frequency antennas are best for locating rebars, cable ducts and tie bars. The high frequency devices can also assess the integrity of reinforced concrete and brickwork, and find small voids, delamination and other defects.
Concrete scans can determine rebar spacing, pattern and depth, the exact location of PVC Conduits, number of rebar mats, concrete cover thickness, position of dowel and rebar splices, wire mesh, dimensions of slab bands.
Left: GPR radargram acquired on a reinforced concrete slab. Diffraction hyperbolae from rebars are used to measure the propagation velocity in the concrete. Right: Cores from the site confirm the GPR results.