Concrete scanning uses ground-penetrating radar (GPR) to investigate shallow features embedded in concrete. It can be used at the surface to find utilities or shallow building structures, such as rebar. The concrete scanner, or GPR unit, contains a source and a receiver. The depth of investigation depends on the source output frequency and source-to-receiver distance. Recordings are processed into interpretable images, and structures or areas of interest will be marked. Useful applications of concrete scanning include utility locating, concrete coring, void scans, and gridscans (to identify building structures).