Investigation of Performance Tests using Bio-derived/Chemical Additives
An industry wide emphasis on sustainable asphalt practices has given rise to increasing use of warm mix asphalt technologies. WMA reduces both binder viscosity and mixing and compaction temperatures by 20-55°C during the asphalt mix production and laydown process. This research investigates several bio-derived WMA additives that act as chemical modifiers with surfactant properties. Two established additives derived from the forest products industry are studied as well as a WMA additive in development that is derived from corn. The WMA material responses are measured for binder testing and mixture testing. All binder testing with the additives was conducted using a Performance Grade (PG) 64-22 binder and the same binder was polymer modified with an SBS polymer to attain a PG 70-22 binder. Dynamic modulus testing on a State DOT approved 10 million ESAL mix design was performed to compare stiffness at a wide range of temperatures and frequencies. The newly developed, corn-derived IDB additive was successful in allowing asphalt to be compacted at a reduced temperature. All additives were added at the same dosage level. The IDB binder and mix test results were comparable to other commercially available WMA additives; however, no particular additive consistently produced the highest or lowest test results.