Ground penetrating radar (GPR) is a great tool for checking potential voids beneath concrete slabs. The concrete on the ground surface may look fine, but the void might already be developing and it's just a matter of time before it collapses. If you have a large area of concern for potential underground voids, scanning with GPR and doing test holes in GPR anomaly areas might be the best option. Geophysicists in Quark Scan are highly experienced in concrete scanning and underground void locating. Give us a call!