Shear-Property-Based Design Approach of Asphalt Mixture in Long and Steep Sections—Taking Togo No. 1 Highway as a Case

The asphalt pavement in long and steep slope sections is more prone to serious rutting distress than that in common slope sections. Therefore, it should be designed with more consideration of anti-rutting property. Since anti-rutting property of hot-mixed asphalt mixture (HMA) is closely related to its shear property, the objective of this study was, relying on the No. 1 Highway reconstructive project in Togo, to propose a design approach to asphalt mixture in long and steep slope sections based on shear property. In this article, a rutting prediction model developed by Tongji University was used to quantify the critical shear strength of asphalt mixture. First, this model was calibrated using field survey data of the existing road, making the model suitable for the Togo No. 1 Highway reconstructive project. Then, the critical shear strength of asphalt mixture was given according to the allowable rutting depth and the calibrated model. Last, four asphalt mixtures with different gradations of AC13-1, AC13-2, Sup13-1, and Sup13-2 were designed using local raw materials, the shear property of which was determined with the uniaxial penetration test (UPT) and the Wheel Track Test. Finally, Sup13-2 was chosen as the optimum gradation for the No.1 Highway reconstructive project with respect to shear property, and its other engineering properties were determined. The concluded design procedure of shear-property-based design approach was given at the end of this article.