Investigation of the aging behavior of cellulose fiber in reclaimed asphalt pavement

Abstract

Cellulose fiber is widely used as an additive to improve the properties of asphalt in stone mastic asphalt (SMA) pavement. As an organic material, however, cellulose fiber occurs continuous aging in the course of service. That will inevitably affect the efficient recycling of SMA pavement. At present, numerous efforts have been made on the regeneration of aged asphalt and the recovery of stable skeleton dense structure, however, the aging behavior of cellulose fiber and its effect on the recycled asphalt mixture have not been attention. Therefore, this paper was carried out to investigate the effects of aging on the conventional properties, surface morphology and chemical structure of cellulose fiber. What’s more, this paper further to discuss the influence of cellulose fiber aging on the performance of SBS modified asphalt mortar. Based on the experimental works, the aging mechanism of cellulose fiber was explored and the effects of fiber aspect ratio on the stress distribution along the fiber axial were analyzed by means of the shear lag theory. The results show that with the aging process, the conventional properties and high temperature performance of cellulose fiber decreases obviously. The resistance of asphalt mortar to cracking is reduced. Cellulose fiber is oxidized and degraded during the process of aging resulting in the decrease of the performance of cellulose fiber. Meanwhile, the original hollow cellulose fiber gradually turns into flattened one after aging. With the decrease of the aspect ratio, the axial stress of cellulose fiber decreases and the interface shear stress increases clearly at the range of stress transfer. The aged cellulose fiber can not play the strong role on the improvement of the properties of asphalt composite matrix.