Research and Measuring Technology Needs to Better Model and Measure Fatigue Crack Development of Thinly Surfaced Asphalt Road Pavements

The root cause of premature failures in relatively thin (<50 mm) asphalt surfaced roads is often a challenge to solve during forensic investigations in South Africa (SA). This description is based on peer review type discussions with forensic investigations experts as well as published research papers. The areas of ignorance or areas where research effort is needed are identified. These observations serve to identify areas of new knowledge needed in terms of actual verification with measurements, measurement technology, and modeling of the observed phenomena. The main objectives of this discussion paper are to highlight the evolution of distress development in asphalt layers starting from the identification and description of the kind of microcracks, effects of microcracks in the debonding of the asphalt layer from lower layer, and vehicle-pavement interactions (VPI) of moving truck wheels focusing on the thin asphalt layer. Specific reference is made to the need to measure and model the effects of bow waves in front of and next to the loaded rolling wheel.