Performance Evaluation of Stone Matrix Asphalt Mixes Using Chitin-modified Bitumen

Abstract

Stone Matrix Asphalt (SMA) has been proven effective in addressing rutting distress in flexible pavement and those with heavy traffic and high temperature. SMA is conventionally produced using VG-40 bitumen due to its superior stiffness and superior capability to resist deformation. However, VG-40 bitumen is expensive, less workable and not readily available. The incorporation of eco-friendly chitin-based polymer derived from shrimp waste into VG-30 bitumen has been studied in the present work. SMA blends were made using VG-30, VG-40, and VG-30 altered with 5%, 7.5%, and 10% chitin by weight of input. The tests done in the laboratory include characterization of aggregate and binder, Marshall mix design, the indirect tensile strength (ITS), tensile strength ratio (TSR) and wheel tracking test (WTT) as prescribed by IRC:SP:79‑2023. Findings indicated that the adjustment of chitin can elevate the stiffness and rutting resistance of the binder. The mixture with 7.5% chitin modified VG‑30 exhibited stability and TSR values similar to that of VG‑40. The rut depths in the wheel tracking tests are found to be within permissible limits at high-temperature loading. So, the modified mixes could be used practically. In addition to performance enhancement, the strategy, reduces the reliance on VG‐40, lowers the material cost and favours waste utilization, thus promoting sustainability in pavement engineering. According to the findings, chitin-modified VG-30 is a technically sound and practically feasible binder for SMA for which Highway agencies can use a durable and eco-friendly solution for long-life pavements.