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Using GPR for dam safety projects

Concrete Inspection

Concrete inspection is of fundamental importance in meeting the challenge of identifying and prioritizing which areas of the dam need to be repaired and which need to be replaced. Amongst the available tools for concrete inspection, GPR has a number of advantages and is particularly well suited to prioritizing for budgeting purposes.

GPR is typically used for to determine the type and location of concrete reinforcement and detecting deterioration in concrete slabs.

Concrete condition assessment can be performed using a ground-coupled GPR system or antennas. A ground-coupled antenna provides clear horizontal resolution, which is sufficient to enable imaging of individual rebars in the top mat, typically not possible with other types of GPR antennas. Ground-coupled antennas are used to collect densely spaced measurements along lines that are oriented so they cross over the top rebar in the upper mat at right angles (or close to a right angle if the rebars are skewed). The amplitude of the radar wave reflection from each rebar is recorded versus its location on the bridge. Relative changes in the rebar reflection amplitudes are typically indicative of the condition of the rebar and/or concrete above it …more