Asphalt Mixture with Scrap Tire Rubber and Nylon Fiber from Waste Tires: Laboratory Performance and Preliminary M-E Design Analysis

Abstract

Scrap tire rubber and nylon fiber are waste materials that could potentially be recycled and used to improve the mechanical properties of asphalt pavement. The objective of this research was to investigate the properties of scrap tire rubber and nylon fiber (R-F) modified warm mix asphalt mixture (WMA). The high-temperature performance was estimated by the Hamburg wheel-tracking testing (HWTT) device. The low-temperature cracking performance was evaluated by the disk-shaped compact tension (DCT) test and the indirect tensile strength (IDT) test. The stress and strain relationship was assessed by the dynamic modulus test at various temperatures and frequencies. The extracted asphalt binder was evaluated by the dynamic shear rheometer (DSR). Pavement distresses were predicted by pavement mechanistic-empirical (M-E) analysis. The test results showed that: (1) The R-F modified WMA had better high-temperature rutting performance. The dynamic modulus of conventional hot mix asphalt mixture (HMA) was 21.8% ~ 103% lower than R-F modified WMA at high temperatures. The wheel passes and stripping point of R-F modified WMA were 2.17 and 5.8 times higher than those of conventional HMA, respectively. Moreover, the R-F modified warm mix asphalt had a higher rutting index than the original asphalt. (2) R-F modified WMA had better cracking resistance at a low temperature. The failure energy of the R-F modified WMA was 24.3% higher than the conventional HMA, and the fracture energy of the R-F modified WMA was 7.7% higher than the conventional HMA. (3) The pavement distress prediction results showed the same trend compared with the laboratory testing performance in that the R-F modified WMA helped to improve the IRI, AC cracking, and rutting performance compared with the conventional HMA. In summary, R-F modified WMA can be applied in pavement construction.

Sustainable Reuse of Waste Tire Textile Fibers (WTTF) as Reinforcements

“…Asphalt mixtures need to be resistant towards permanent deformation and cracking caused by a lack of foundation-bearing capacity and temperature cracking (climatic effects) [ 94 ]. For example, fatigue cracking of asphalt pavements is more prevalent in cold climate regions, while asphalt rutting more generally occurs in hot climatic regions [ 95 ]. The main advantages of rubberized asphalt mixtures are to delay reflection cracking, reduce traffic noise, minimize maintenance cost, and obtain hardened asphalt mixtures at high service temperatures since tire rubbers do not melt under heat and do not crack at low temperatures [ 26 , 28 ].…”

“…Among the various modifiers for asphalt reinforcement, WTTF as a sub-product of ELT treatment have gradually attracted more attention due to their economic and environmental benefits instead of being disposed of in landfills or used in energetic valorization [ 98 ]. Waste tire-derived textile fibers have the potential to increase the toughness and fracture resistance of hot mix asphalt (HMA), as well as serve as stabilizers to hinder drain down of the asphalt binder (porous asphalt mixtures and stone mastic asphalt (SMA) mixtures) [ 94 , 95 , 99 , 100 ]. WTTF can be considered as a cheap alternative for common fibers such as PP, polyester, asbestos, cellulose, carbon, glass, nylon, coconut, basalt, steel and aramid to lower the use of virgin raw materials and develop asphalt mixtures with good resistance to aging, fatigue cracking, moisture damage, bleeding and reflection cracking [ 99 ].…”

“…WTTF can be considered as a cheap alternative for common fibers such as PP, polyester, asbestos, cellulose, carbon, glass, nylon, coconut, basalt, steel and aramid to lower the use of virgin raw materials and develop asphalt mixtures with good resistance to aging, fatigue cracking, moisture damage, bleeding and reflection cracking [ 99 ]. Only few studies investigated the reuse WTTF in asphalt binder modification to induce superior performance of flexible road pavement layers subjected to traffic loading [ 94 , 95 ]. As an early step to introduce textile fibers derived from ELT in asphalt formulations, Putman and Amirkhanian [ 48 ] used cellulose, polyester, scrap tire and waste carpet fibers (0.3% wt.…”

“…To limit global warming and reduce greenhouse gas (GHG) emissions, the asphalt industries made recent efforts to develop new asphalt mixtures called warm-mix asphalt (WMA), which are suitable for lower construction temperatures without the sacrifice of properties [ 103 ]. As an example of limited research focusing on WMA reinforced with recycled fibers, Jin et al [ 95 ] investigated the effect of both scrap tire rubber and ELT fiber on WMA modified with Sasobit (synthetic commercial wax). They observed higher crack resistance of tire rubber–fiber-modified WMA by 24.3% and 7.7% compared to conventional HMA and conventional asphalt mixture, respectively [ 95 ].…”

“…As an example of limited research focusing on WMA reinforced with recycled fibers, Jin et al [ 95 ] investigated the effect of both scrap tire rubber and ELT fiber on WMA modified with Sasobit (synthetic commercial wax). They observed higher crack resistance of tire rubber–fiber-modified WMA by 24.3% and 7.7% compared to conventional HMA and conventional asphalt mixture, respectively [ 95 ].…”