Permanent deformation performance of binders and stone mastic asphalt mixtures modified by SBS/montmorillonite nanocomposite

Accumulated strain in asphalt layer or rutting is one of the major deterioration in asphalt mixtures that occur in high temperatures. Stone mastic asphalt have gap graded structure and have higher binder content than hot mix asphalt which indicates that utilizing additives to modify binder have significant role in enhancing the performance of mixture. Also, Due to high amounts of bitumen, there is the potential of binder draindown, so the use of fibers or polymers is inevitable. With the advent of nanomaterials in civil engineering applications, especially in pavement engineering, nanoclay particles have shown promising results in enhancing the properties of bitumens. In this paper the effects of montmorillonite Nanoclay on rutting behavior of polymer modified bitumen were investigated. Also, the influence of montmorillonite Nanoclay on permanent deformation behavior of mixtures containing fibers and polymers were studied. The Nanoclay was added to asphalt binder (1, 2, 3 and 4% by the weight of the binder). The rutting behavior of bitumens were assessed based on Multiple Stress Creep Recovery (MSCR) test. The permanent deformation resistance of SMA mixtures was investigated through the Hamburg wheel track and dynamic creep tests. Results indicated that in comparison with modified bitumens, binder modified with 4% nanoclay and 5% SBS has the lowest Jnr and highest percent recovery value which gives rise the original binder to better resistance against rutting. Results revealed that the SMA mixture modified by SBS have superior performance against rutting than SMA mixtures containing fibers. Moreover, among the different nanoclay modified SMA mixtures, mixture modified by 3% montmorillonite have the best performance against permanent deformation. (C) 2019 Elsevier Ltd. All rights reserved.