Evaluation of permanent deformation of multilayer porous asphalt courses using an advanced multiply-repeated load test

Multilayer porous asphalt (PA) courses have the advantages of runoff mitigation, rainwater management and noise reduction. The objective of this paper was to develop an advanced multiply-repeated load test which can effectively simulate the field conditions, including confinement condition, actual temperature distribution, and axle load spectrum. And it was used to evaluate the rutting resistance of multilayer PA courses in this study. Rutting resistance of single, double, and triple-layer PA courses and traditional dense graded asphalt courses (control) were investigated under three axle load spectrums. Rutting resistance indicators, such as multiple flow number and loading sensitivity curve, were utilized to evaluate the rutting resistance. The result indicates that the percentage of heavy axle loads in the load spectrum plays a vital role in the rutting development of multilayer PA courses. The rutting resistance of four multilayer asphalt courses was compared and the control was the best, following by the single, double, and triple-layer PA courses. The addition of fiber in porous asphalt mixture can remarkably improve the rutting resistance of multilayer PA courses. Based on the results, it can be concluded that the single-layer PA courses can be used in heavy traffic roads and has been validated by field constructions. The double and triple-layer PA courses are only recommended in medium traffic roads, and the performance in the field need further investigated and validated.