The fatigue life extension prospect of calcium alginate capsules in porous asphalt

Self-healing technology, such as encapsulated rejuvenator, induction heating or combination of the above two methods, has been demonstrated to be a promising autonomic crack healing mechanism for porous asphalt. With the advantage of low cost, environmentally friendly and excellent performance, the calcium alginate capsules encapsulating rejuvenator showed promising effect to promote the crack healing in asphalt concrete. However, the healing effect of the calcium alginate capsules on the damage from fatigue loadings is still unknown, therefore became the research focus of this study. To this aim, the calcium alginate capsules were produced and incorporated into the porous asphalt (PA). A laboratory ageing process was performed on the PA to simulate the situation when asphalt pavement prone to cracking and a healing needs to take place. Afterwards, the four-point bending fatigue test (4PBF) was employed to characterize the fatigue resistance of the PA specimens. A 24-hour-rest period was carried out to allow the healing of fatigue damages. Additionally, a 4PBF testing and healing programme was carried out to evaluate the fatigue damage healing efficiency of the calcium alginate capsules healing system. It was found that the capsule healing mix showed a higher fatigue life than the reference mix, but the results were a bit scattered which might be caused by the capsule distribution which determines whether the healing takes place on the damage site or not.