Low Temperature Performance Characterization of Bio-Modified Asphalt Mixtures Containing Reclaimed Asphalt Pavement

摘要

The sustainability movement in paving materials has led to the increased use of reclaimedasphalt pavement (RAP). New developments in this area in the recent past include the use ofbio-modified asphalt binders (BMB) such as those containing bio-oils derived from swinemanure. The current study examines the low temperature properties of RAP and virgin BMBmixtures to determine if these mixtures exhibit improved low temperature performance ascompared to conventional hot mix asphalt (HMA).Disk-Shaped Compact Tension (DC(T)), Superpave Indirect Tension, and Acoustic Emissiontests were employed to characterize low temperature properties of the asphalt mixtures. BMBmixtures exhibited higher DC(T) fracture energies as compared to HMA at all RAP levels. Inaddition, BMB mixture fracture energy displayed a reduced dependence on RAP content, as thedifference in average fracture energy between BMB and HMA mixtures increased with higherRAP contents. Furthermore, BMB mixtures displayed consistently higher creep compliancewhich indicates that these mixtures can alleviate thermal stresses more easily than HMA.A recently developed acoustic emission testing procedure evaluated the effects of BMB as wellas RAP in the mixtures. The overall trends identified through AE testing were consistent with thefindings from the DC(T) and ID(T) tests. In addition, AE results suggested a fundamentalchange in the behavior of the BMB RAP mixture relative to the HMA RAP mixture, e.g., arejuvenating effect. In general, it was observed that BMB RAP mixtures exhibited superior lowtemperature cracking behavior as compared to HMA mixtures.