Energy-absorbing particles for enhanced mechanical performance of asphalt's aggregate skeleton

Abstract

This paper evaluates the feasibility of using 3D-printed lattice metamaterials as an alternative to capsules containing rejuvenators to enhance the self-healing capability of asphalt. The original purpose of these capsules is to encapsulate a rejuvenator and ensure its gradual release under load. However, the cellular structure of the capsules, along with their inherent energy absorption properties, may have a non-negligible physical impact on the asphalt's aggregate skeleton, which is not well understood but could influence the asphalt performance. To address this, lattice structures with a wide range of stiffness, strength, and energy-absorption properties were firstly designed and 3D-printed. Subsequently, the mechanical behaviour of a composite granular medium composed of granite aggregates and either cellular capsules or 3D-printed lattices was investigated. Cyclic and monotonic experiments were conducted on this composite granular medium, which represents the aggregate skeleton of asphalt. Lastly, its mechanical response, plastic deformation of lattices and capsules, and the crushing behaviour of aggregates were measured. Through a comparative analysis of results obtained from lattices with significantly different mechanical and energy-absorption properties, it was found that: i) capsules do induce physical changes to the aggregate skeleton of asphalt; ii) despite design constraints, lattice metamaterials can be successfully 3D-printed and tailored to meet specific requirements; iii) Voronoi lattices emerge as a potential alternative to replace the capsules.