Development of porous asphalt mixture with bio-based epoxy asphalt

The high porosity of porous asphalt mixture improves wet skid resistance on pavements and reduces storm water runoff from pavements, but it also makes the mixture prone to raveling, and thus low durability, in the field. This study aims to improve the durability and strength of porous asphalt mixture by formulating bio-based epoxy asphalt binder (BEAB) and improving its mixture design. In the study, a BEAB formula was firstly developed using an epoxidized soybean oil (ESBO) that is considered as a renewable resource. The performance of porous asphalt mixture containing BEAB was then tested and compared with regular porous asphalt mixtures. Based on laboratory test results and analysis, the maleic anhydride is better than several other curing agents for ESBO when mixed in asphalt. The finally selected BEAB formula contains the ESBO, the MA, and neat (control) asphalt at mixing ratios of 7%, 5%, and 88%, respectively. Compared to the control asphalt, the formulated BEAB may improve the raveling resistance and stability of porous asphalt mixture without reducing its permeability. In practice, to achieve balanced pavement performance, a 4.75-mm nominal maximum aggregate size open gradation with an optimal BEAB content is recommended.