Journal of Cleaner Production 217 (2019): 456-468.
Using sustainable, renewable substances that can be locally-sourced instead of petroleum-based asphalt binders would be better for our environment. Replacing a small portion (maximum of 6%) of asphalt binder with three different types of lignin was investigated to determine its effects on aged and unaged asphalt binder and mix. Commercially available Kraft lignin, lignin precipitated from black liquor in the laboratory, lignin produced from rice hulls in the laboratory using a deep eutectic solvent, and a standard asphalt binder (control) were evaluated. Lignin improved the high temperature performance grade. All lignin-modified binders showed higher strain tolerance than unmodified binders in strain sweep tests. Lignin precipitated from black liquor and lignin produced from rice hulls improved the long-term aging index. Rutting, cracking, and moisture damage susceptibility tests were performed on an asphalt mix prepared with 6% lignin precipitated from black liquor asphalt binder. Improved rutting resistance was observed from the lignin-modified asphalt mix, without sacrificing moisture-induced damage resistance. Better cracking resistance with respect to increased flexibility index was observed according to the semi-circular bend test. Replacing petroleum-based binder with up to 6% of lignin precipitated from black liquor is practicable for hot mix asphalt, and may be feasible in the lower temperature warm mix asphalt process.
