Mechanistic Analysis and Durability of Thiophene Paving Mixtures

Abstract

When compared to conventional bitumen, thiophene bitumen produced in northern Iraq is abundant and inexpensive (on the order of 125 USD/ton). This type of bitumen contains higher sulfur content in terms of the heterocyclic compound (not elemental sulfur); furthermore, long-term aging (LTA) effects are not considered in research on this type of bitumen for use in paving mixtures. In this research, the influence of LTA at 85±3°C for 120±0.5 h on thiophene mix asphalt (TMA) properties in terms of stability, indirect tensile strength at 25 and 60°C, rigidity, resilient modulus, and tensile strength ratio were determined and compared with hot-mix asphalt (HMA) containing conventional bitumen. Under a 40-kN dual load with a 105 mm wheel radius, pavement responses in terms of fatigue strain (εtmax), rutting strain (εcmax), and surface deflection (Δzmax) were analyzed using multilayer elastic analysis software (BISAR). The test results of TMA showed slightly higher stability, indirect tensile strength, and resistance to moisture damage (higher durability) with a slightly lower resilient modulus than HMA. Generally, results showed that the performance of TMA at a mixing temperature of 130°C is considered similar to that of HMA under the effect of LTA. Furthermore, using thiophene bitumen can reduce the mixing temperature of paving mixes above about 20°C in a manner comparable to HMA. In addition, the results also indicated that LTA-TMA showed 10% higher fatigue life than LTA-HMA. In addition, it was found that the granular base layer in the LTA-TMA pavement system can be reduced by 55%.