Performance of Thin Asphalt Concrete Overlays

The modulus of asphalt concrete (AC) layers in a pavement system is one of the primary parameters that affect the performance of the pavement. This modulus is often difficult to measure however, especially for thin AC overlays over Portland cement concrete (PCC) pavements. In this paper, seismic non-destructive testing technology based on the use of stress waves is proposed as a useful tool for determining the modulus of these asphalt concrete layers on PCC pavements. To that end, a test section was constructed on highway IH-20 using nine different mixture designs. Results from field tests conducted on thin AC pavements over PCC pavements indicate that the change in the modulus of AC is strongly affected by the type of mixture and the aggregate used in the design. Based on the results of the portable seismic pavement analyser (PSPA), the change in modulus of different types of AC was observed, and a statistical test was conducted to examine the change in modulus of each test section. This research confirmed that differences in the modulus of thin AC pavements over PCC pavements can be monitored using PSPA equipment at the early stages of the thin AC pavements.