Rheological Properties and Application of Molasses Modified Bitumen in Hot Mix Asphalt (HMA)

The use of molasses as a replacement for bitumen could benefit the pavement industry by improving the performance of the pavement or by lowering its cost. An experimental investigation was carried out to investigate the effect of molasses with different moisture contents on the property of hot-mix asphalt (HMA). Bitumen binders (BB) containing 5%, 10%, 15%, and 20% molasses were investigated as molasses modified binders (MMB). Molasses with 24.9% and 5.02% by weight of water were used to investigate the effect of moisture on the MMBs. In addition to the conventional binder tests, additional tests such as the Fourier transform infrared (FTIR) test, amplitude and frequency sweep test, performance grade (PG) test, and multiple stress creep recovery (MSCR) test were performed. The results indicated that most of the properties of the MMBs improved with the reduction in the moisture content of molasses but worsened with the percentage replacement of molasses. The IR spectra show that the carbonyl index decreased with an increasing amount of molasses. The control grade PG58 was improved to PG64 and PG70 when the base binder was modified with molasses and aged with rolling thin film oven (RTFO) consecutively. At a temperature of 58 °C, non-recoverable creep compliance of 3.2 kPa (Jnr3.2kPa) was decreased for each MMB, which leads to improved rutting potential. At a temperature of 64 °C, the Jnr value was decreased only for the MMB containing 5% molasses, and then gradually increased for the remaining MMBs. Generally, the study revealed that low moisture content molasses could be used as a partial replacement for bitumen to enhance the rheological properties of the bitumen.