Performance Evaluation of Superflex Modified Thin Asphalt Overlay

The use of thin asphalt overlay is an effective way in preserving and maintaining the road surface. In this study, the virgin asphalt was mixed up with Superflex modifier at varied concentrations to get the modified asphalt overlay, and the optimum modifier content was 15% by weight of the total mix. Aggregate gradation of the overlay was acquired by means of volume method, and the optimal asphalt content was obtained through Marshall mix design. The performance of the modified overlay mixture evaluated in the laboratory included high-temperature stability, moisture susceptibility and skid resistance. In order to investigate the effects of different thickness levels and structure patterns, four thin overlay sections were paved on route G321 in Guangdong, China. Deflection, skid resistance, permeable performance and roughness were inspected four times in the following six years. The laboratory test results showed that all the testing indices satisfied the criteria specified in China. The field inspection data proved that the thin asphalt overlays evaluated in this study performed well in terms of skid resistance, permeable performance and roughness in every section, without sharp damage on the surface. It can be concluded that the Superflex modified asphalt mixture can be used as thin overlay and this technology is worth popularizing.