Mechanical activation assisted of biobased encapsulated rejuvenators to promote asphalt self-healing

Abstract

This research aimed to evaluate the effect of the addition of biobased encapsulated rejuvenators on the self-healing properties of asphalt mixtures. With this objective, polynuclear capsules were synthesised using alginate biopolymer as encapsulating material and sunflower oil as rejuvenator. The capsules were physically and mechanically characterised by optic and scanning electron microscopy techniques as well compressive tests. Four types of semi-dense asphalt mixtures were manufactured, varying in capsule content: 0.0%, 0.125%, 0.25%, and 0.5%wt. The self-healing properties of each mixture were evaluated based on mechanical cracking, capsule activation, and healing level quantification processes. A new confined uniaxial compression test was developed for capsule activation. The self-healing capacity of the asphalt mixtures was determined under force and fracture energy criteria. Statistically significant differences in the healing variables were analysed through one-way ANOVA and Tukey post-hoc tests. The main results showed that the capsules presented regular spherical morphology and high mechanical stability to resist the mixing process at high temperature. The new activation approach effectively activated the alginate-based capsules inside the asphalt mixtures promoting their self-healing. Force and energy crack-healing criteria improved with the addition of capsules in the asphalt matrix, with healing values being higher for the force criterion than those for the energy one. Finally, the addition of capsules in a content equal or greater than 0.25%wt. significantly improved the self-healing properties of the asphalt mixtures.