Development of improved porous asphalt mixtures with high porosity levels

Abstract

Porous asphalt (PA) mixtures are gaining wider acceptance in pavement construction due to their benefits in terms of road safety, noise mitigation and stormwater management. Increasing demands, such as those imposed by climate change, require the design of mixtures that provide enhanced functional properties, while keeping the same durability of conventional porous asphalt mixtures. This study proposes different experimental PA mixes with higher air voids content and suitable structural capability than a conventional PA mixture. The functionality of the mixtures was evaluated in accordance with total and interconnected air voids, while the mechanical performance was assessed in terms of raveling resistance both in dry and wet conditions, tensile strength, and moisture sensitivity. The binder drain down was also verified. In a first stage, the experimental results were analyzed through descriptive and inferential statistics tests. As multiple responses were obtained, principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) were applied to explore the association pattern among the test results and experimental designs. The study concluded that PA mixes with air voids content of up to approximately 28% and admissible values of resistance can be designed. The use of polymer modified binder (PMB) and the inclusion of fibers and hydrated lime (HL) was essential for the formulation of the mixes.