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Yes, GPR can measure depth and thickness. The speed at which the GPR signal travels depends on the permittivity of the material being scanned. The depth to a target can be calculated based on length of time it takes for the GPR signal to travel from the transmitter to the target and back to the receiver. It the depth to a specific object is known, a calibration can be conducted in-situ to determine the coefficient of permittivity of the material being scanned. This information can then be used to calculate the depths of other objects at unknown depths under similar site conditions.

No. There are several research papers, which suggest possible methods, but these are not accurate or reliable. Alternatively, there are cover meters, which use pulse induction, which can provide rebar diameter estimates. In our experience, these are not particularly reliable and are prone to being affected by other adjacent reinforcement. Sandberg strongly recommends a small local break out to expose the reinforcement at an intersection. This is reliable and determines the reinforcement detail of both the longitudinal and transverse bars.

Yes, GPR can detect voids below concrete slabs. Voids produce a strong characteristic reflection. The planar extent of the void can be determined, however, the actual depth of the void itself (from top of the void to bottom of the void) cannot be accurately measured. Sandberg successfully carry out many such surveys; warehouse slabs being the most common. It is normal to combine the void survey with a reinforcement survey to identify different construction detail and missing or poorly placed reinforcement.