Aggregate angularity effect on porous asphalt engineering properties and performance

Abstract

Porous asphalt is a flexible pavement layer with highly interconnected air voids constructed using an opengraded type of aggregate. The aggregate shape and surface texture serve a vital function in determining the engineering properties and performance of porous asphalt. The angular aggregates with clearly defined fracture faces and sharp edges encourage better interlocking between the aggregates' skeleton structures, which makes them preferable to use in asphalt mixtures. This study evaluates the effect of aggregate angularity on the engineering properties and performance of porous asphalt using both conventional and empirical particle index test methods. The term “engineering properties” refers to the experimental works determining resilient modulus and stability, whereas “performance” deals with the porosity and durability characteristics of porous asphalt caused by variations in the particle index number (Ia). A laboratory data analysis shows that angular particles provide a larger Ia number than non-angular particles. Furthermore, resilient modulus and stability properties significantly improve when angular aggregates are applied. The angular particles provide high mixture porosity but cause poor durability performance of porous asphalt against abrasion loss. Some improvements are suggested to enhance the strength properties and performance of porous asphalt on the basis of engineering applications.