Toner-modified asphalt demonstration projects

Abstract Although there has been interest in recycling of toner in asphalt binder, few studies have been conducted despite the potential saving benefits to the photocopier and pavement industries. This research project describes the results of three demonstration projects in the Laredo, Houston, and Pharr districts in Texas where waste toner was used as an asphalt binder modifier. For each of these projects, a binder design was performed, including blending time, performance grading, storage stability, and mixing and compaction temperature calculation. The performance-grade (PG) properties of the toner-modified asphalt binders used in each test section varied according to the amount of polymers in the toner. Objectives of the research included determining the toner levels needed to arrive at a given PG, as well as a better understanding of the effect of toner level on the PG properties of a binder. Test results indicate that the stiffness of the blend increases at all temperatures as the percentage of the toner content present increases. This stiffening effect is more pronounced when the level of toner content is at higher levels. Results also show that 2 h of blending time is sufficient to achieve a homogeneous toner–asphalt mix; significant storage stability problems are expected regardless of the level of toner in the blend; and mixing and compaction temperatures stay at reasonable levels.