Effect of encapsulated pyrolytic rejuvenator derived from end-of-life mining tyres on the self-healing properties of aged bitumen

Abstract

This study aimed to evaluate the use of biopolymeric capsules based on alginate and a pyrolytic rejuvenator derived from end-of-life mining tyres to enhance the self-healing properties of aged bitumen in asphalt pavements. Capsules were produced using the jet vibrating technique settled with nozzle sizes of 300, 450, 750 μm and CaCl2 hardening solutions at 2%, 5%, and 8% by total weight (wt.) of bitumen. Their mor-phological, thermal, and mechanical properties were analysed. Self-healing performance was evaluated by in-corporating 0.5%, 1.0%, and 2.0% wt. capsules into long-term aged bitumen and testing healing efficiency through cyclic fracture-healing tests over 6 and 24-hour periods. The main results showed that capsules pre-sented mechanical and thermal stability for the paving conditions. An optimal capsule design was achieved using a 750 μm nozzle size and 2% wt. CaCl2 solution. Finally, a dosage of 1% wt. of the optimal capsule design optimised the self-healing property.