Asphalt self-healing with encapsulated rejuvenators: effect of calcium-alginate capsules on stiffness, fatigue and rutting properties

Asphalt self-healing with encapsulated rejuvenators is a new promising approach to extend the service life of asphalt pavements. Although the research performed so far has demonstrated the crack healing mechanism, no formulation/design for the capsule-bituminous mixture system, aiming to optimize its performance properties, has yet been proposed. This study investigates the effect of calcium-alginate capsules, containing sunflower oil, on the mechanical properties of bituminous mixtures. Performance-related properties of a continuously-graded bituminous mixture (stiffness, fatigue and rutting) were evaluated for different dosages of capsule incorporation (0.50, 0.75 and 1.00 wt%). The results showed that the stiffness properties of the bituminous mixture are affected by capsules and that this effect evolves with bitumen ageing. The stiffness modulus after ageing treatment was close to the bituminous mixture with 0.50 wt% and 0.75 wt% capsules and to the reference material. The fatigue resistance of all bituminous mixtures was similar and the bituminous mixtures with capsules did not show an improvement in fatigue resistance after resting, in comparison with the reference material. However, the results clearly indicated that the rejuvenator was released from the capsules and diffused into the bitumen. The bituminous specimens with capsules showed a strong rutting resistance, and the performance was even improved after the rest period.