Detection and survey of interface defects within a pavement structure with ultrasonic pulse echo

Abstract

A pavement structure, which contains artificial interface defects, has been built on the full scale accelerated pavement testing facility of IFSTTAR in Nantes. This test section is made of two bituminous layers (8 cm thick base layer, and 6 cm thick wearing course), over a granular subbase. Several types of defects have been included at the interface between the two asphalt layers. Rectangular debonded areas of different size (of longitudinal or transversal direction) have been created artificially, using different techniques (sand, textile, absence of tack coat). The construction has been carried out by a road construction company, using standard road works equipment. Then, the pavement fatigue testing facility has been used to apply traffic loading on this pavement, to study the effect of such sliding interfaces on the mechanical behaviour of the pavement, and the evolution of the defects with traffic. The pavement structure has been monitored with several non-destructive methods. The paper presents the survey of the test section with an Ultrasonic Pulse Echo method. This Non Destructive Technique used high frequency wave propagation. It has been able to detect and locate interface defects. The method can also be used to evaluate material properties.