Tall oil pitch, a Kraft pulping process co-product, is a resinous substance containing fatty acids, resin acids and neutral compounds, analogous in some of its properties to bitumen. Laboratory evaluations indicate that tall oil pitch strongly influences rheological and adhesive properties of asphalt cement. The addition of a small percent of tall oil pitch lowers the viscosity of asphalt cement significantly. A combination of tall oil pitch and asphalt cement is compatible, forming a stable homogenous blend. Marshall properties are good and comparable to conventional asphalt cement mixes. Several field trials using tall oil pitch were conducted by British Columbia Ministry of Transportation and Highways between 1989 and 1992. In these projects, tall oil pitch was used as a reclaimed asphalt pavement revitalizing additive or asphalt cement extender. The field trials demonstrated that paving mixes containing tall oil pitch could be produced and installed by a standard mixing plant and paving equipment. The workability of tall oil pitch and associated health and safety hazards were comparable to conventional asphalt paving. Tall oil pitch used in field trials was competitively priced against asphalt, offsetting increments in cost of construction. To the present date, the roads paved with tall oil pitch modified asphalt are in very good condition. (A)
Abstract