Ground penetrating radar system for detection of desiccation cracks in soils

In this paper we explore a relatively simple, non-destructive, indirect technique using a ground penetrating radar (GPR) system to detect cracks that form and propagate inside a soil specimen during desiccation. Although GPR devices have been used for multiple applications, their use in the detection of small cracks (few millimetres wide), has not been demonstrated yet. The experiments and the methodology used to test the accuracy of a small commercial GPR device for crack identification are described. The main objective was to identify what type of signals and what crack width can be detected using the GPR device. The results indicate that cracks of one or two millimetres wide can be detected depending on its position and shape. On the other hand, sub-millimetre cracks are undetectable with the currently existing devices in the market. In spite of the limitations the GPR method can be useful to find time-related bounds of when the cracks appear, and to point at their location. Because the GPR systems are in constant evolution this technique could become a very versatile and convenient method to scan soils under different kinds of processes both in the laboratory and in the field.