Fatigue resistance of bituminous layers incorporating reclaimed asphalt pavement

This paper presents the results of an investigation into the fatigue performance of a 20mm Binder Course Asphalt Pavement Mix incorporating Recycled Asphalt Pavement (RAP). For the study, a series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material, was selected as the control mix for the investigation. A Circular Wheel Tracker (CWT) was developed in order to simulate the dynamic loading conditions of a rolling wheel and to study the initiation and growth of fatigue cracks in an asphalt pavement mix. The CWT was commissioned within a temperature-controlled room with a customised data acquisition system. The test specimens were subjected to dynamic loading in the CWT and the dynamic strain on the underside of the slab was monitored throughout the test. A digital image processing technique was also used to measure the crack area and crack length at the underside of the test specimen. Parallel to this a separate testing programme was undertaken, whereby the fatigue resistance of bituminous mixtures incorporating same RAP contents was assessed using the indirect tensile fatigue test as described in BS DD ABF:1997. The results from these parallel strands are compared, and the performance of the various mixes incorporating RAP is assessed.