Production and Characterization of Polymeric Capsules Containing Rejuvenators for Asphalt Mixtures Self-healing Purposes

Pavement distresses are a result of loading and natural ageing, though asphalt mixtures have self-healing capacity because the asphalt binder is a self-healing material. It has been demonstrated before that the asphalt binder drains to the cracks, closing it, if sufficient time and adequate temperature conditions are given. In practice, this mechanism is highly inefficient because traffic is not interrupted, and in-service temperatures are not high enough. Self-healing can be accelerated with capsules containing rejuvenators. The released rejuvenator modifies locally the rheology of the binder to drain faster to the crack. This paper investigates the effect of fabrication conditions of polymeric capsules, containing sunflower oil, to the morphological, geometrical, thermal, and mechanical characteristics of capsules. Capsules were produced by ionotropic gelation of sodium alginate and calcium chloride, using extrusion and air-atomization methods. The effect of supplementary high temperature conditioning and cross-linking with glutaraldehyde were investigated. The results showed that the amount of oil encapsulated in capsules depends on the sodium alginate and calcium chloride concentrations. Thus, these concentration values affect the size and mechanical properties of capsules. The mechanical strength increases substantially with the supplementary treatment. Finally, the capsules showed to significantly improve the self-healing ability of bituminous mastic beams.