Rheological characterization of asphalt binders modified with soybean fatty acids

• As a source of soybean fatty acids, soybean acidulated soapstock (SAS) serves as a viable additive for asphalt binders.
• Findings suggest that SAS could be used as a fluxing agent for stiff, hard and viscous asphalt binders.
• Findings suggest that adding a small amount of SAS reduces thermal stress development in asphalt binders.
• Low temperature effects of asphalt binders modified with soybean acidulated soapstock appear to be crude oil source specific.

This investigation examines rheological properties of asphalts blended with soybean acidulated soapstock, a relatively low-cost and highly concentrated source of soybean fatty acids. Rheological tests indicate that as soybean acidulated soapstock is added, binders become softer, less stiff and their high temperature viscosities are reduced. The addition of 1% soybean acidulated soapstock reduces thermal stress accumulation. These findings suggest that soybean acidulated soapstock could be used as a fluxing agent (i.e., consistency reducer) for stiff, hard and viscous asphalt binders, increasing their workability and may improve low temperature performance of an asphalt binder by reducing thermal stress development.