Identification of deep-rooted transverse cracks using Ground Penetrating Radar

Executive summary Transverse cracking is a surface distress resulting from various mechanisms appearing in the pavement and their occurrence proves improper action of the structure, which, in a long run will be subject to accelerated degradation. The proper evaluation of the progress of cracking is certainly helpful in finding out the origin of this type of damage; therefore, also in the correct selection of the repair technology. The use of GPR (Ground Penetrating Radar) as an auxiliary tool in assessing the structural condition of the pavement in terms of identification of transverse cracking is not a new practice. However, it is still a complicated task due to many external factors which may distort the result or even prevent analysis of data, especially in terms of interpretation of the obtained radar images. This article presents the case study for the practical use of the method of GPR inspection of the transverse cracks structure to analyse the process of restoring transverse cracks in bituminous pavement. This procedure is based on the earlier catalogue of the GPR manifestations of the elements of deep cracking structure and requires precise synchronization of the GPR measurement with cracks observed on the pavement. Explicit manifestations are only visible in expanded cracks, where the zone of material changes in the vicinity of the cracking surface has a width of at least one decimetre. Such defects usually result from the long-lasting operating process, and their presence in the deeper layers of the structure is an evidence of breaking continuity of mechanical consistency of the foundation under the cracking line.