Automatic Detection of Water Inside Concrete Slabs Using Ground Penetrating Radar

Abstract

GPR is used generally as a non-destructive method of inspection for structures and finding defects in concrete slabs. In this thesis GPR is used in detection of water inside cavities of concrete hollow core slabs. The feasibility of several signal processing techniques and methods were studied during the literature review. Performance of three different GPR systems from different companies were tested with an experimental setup consisting of a standard hollow core slab which had variable amount of water in its cavities. Data from GPRs were processed with the developed algorithm which includes filtering, reference point calculation, range gating and location the peaks. Presence and amount of water was successfully detected with radar from GSSI company which was the most accurate of the three with a central frequency of 2.7 GHz. The radar from GSSI was chosen for its performance and ability to detect lower amounts of water inside the cavity.

The developed algorithm consists filtering, reference point calculation, range gating and location of peaks and comparing them to a reference point. The algorithm assumes that the geometry of the hollow core slab is known. Results, possible future research and analysis of the feasibility of GPR systems in water detection are presented and discussed.