Bio-binder development using soya pitch oil: chemical, rheological and performance evaluation

Bitumen is a petroleum-based non-renewable material used as a binder in asphalt mixtures. To address resource depletion concerns, this study aimed to use Soya Pitch Oil (SPO), a by-product of soybean fatty acid distillation, as the bio-modifier for VG30 binder. The dosages of SPO used were 0–20% and evaluated through physical, chemical, rheological and moisture-related analyses. The results indicated that incorporation of SPO reduces mixing and compaction temperatures, which means lower energy consumption. Rheological measurements performed with a frequency sweep, MSCR and LAS tests showed that SPO led to a decrease in complex modulus and rutting resistance, and a marked improvement in fatigue performance. The PAT test showed that SPO improved moisture resistance and aggregate-binder adhesion. Further, the cost analysis has shown that partial replacement of VG30 with SPO reduced binder cost, supporting its economic feasibility. The overall performance of the SPO-modified bio-binders suggests that SPO could be viable, sustainable, durable, moisture-resistant and cost-effective materials for pavements.