Investigation of the self-healing and rejuvenating properties of aged asphalt mixture containing multi-cavity Ca-alginate capsules

Abstract

Asphalt is one of the most widely used pavement materials, but is prone to ageing, creating cracks and further deterioration until failure. Self-healing capsules mixed into asphalt mixture can release agents to over time improve healing cracks and can effectively rejuvenate aged asphalt and extend the lifetime. In this paper, in order to explore the effect of Ca-alginate capsules on the self-healing and rejuvenating properties of aged asphalt concrete, and to clarify the mechanism of self-healing promotion, multi-cavity Ca-alginate self-healing capsules are mixed into dense asphalt concrete, and then exposed to thermal-oxidative accelerated ageing and ultraviolet ageing in laboratory. 3-point bending test and fracture-rest-refracture test are used to study the effect of self-healing capsules on mechanical properties and self-healing capability of aged asphalt mixture. The chemical component, rheological property and flow behavior of asphalt binders are used to demonstrate the rejuvenation of aged asphalt concrete. It is found that Calcium alginate capsules have little effect on the initial mechanical properties of the asphalt concrete, and ageing increases the stiffness of asphalt concrete with and without capsules and reduces their fracture energy. The capsules can effectively improve the strength healing rate and fracture energy healing rate of asphalt concrete. The aged asphalt concrete with capsules can also reach same self-healing level with ordinary virgin asphalt concrete without capsule. These are mainly because sunflower oil is released into the aged asphalt mortar after the capsules is broken, which increases the saturate and aromatic lost during the ageing process of the asphalt. It can effectively recover the rheological properties and flow property of aged asphalt binder, thereby improving the self-healing performance. Multi-cavity self-healing capsules enable in-situ rejuvenation of aged asphalt while healing cracks.