Effect of Lignin Type as an Additive on Rheology and Adhesion Properties of Asphalt Binder

Abstract

Utilization of alternative asphalt binders and additives from renewable sources, given the scale and the impact of the asphalt pavement industry, is an important step toward a sustainable future for the surface transportation infrastructure. Among several sources available for harvesting sustainable construction materials, bio-based materials from agricultural feedstock are known to be one of the most reliable, renewable, environmentally friendly, and economically feasible solutions to achieve this goal. Lignin, one of the most abundant materials in nature, is the byproduct of several industries, specifically pulp processing and biofuel production facilities. Given its physical properties, the use of lignin as a partial replacement for petroleum-based asphalt binder has been studied and proven promising. However, lignin’s properties vary depending on its source and processing techniques. Therefore, incorporating lignin in asphalt binders can result in different mechanical properties, depending on its type and chemical composition. The present study was undertaken to evaluate the effect of three different lignin types, when used as an asphalt binder modifier, on the rheological properties of the asphalt binder, aging characteristics, and its adhesion to different aggregates. This study’s findings showed that, when incorporated in an asphalt binder at the same amount, different lignin types have significantly different effects on asphalt binder blends’ rheological, aging, and adhesion properties. Different rheological, aging, and adhesion properties of the binders result in different mechanical characteristics in asphalt mixes containing lignin-modified asphalt binders.