Combining asphalt-rubber (AR) and fast-pyrolysis bio-oil to create a binder for flexible pavements

Abstract

The bio-oil from fast pyrolysis is mainly a product of the recycling of waste materials. This is a viscoelastic material, and after a heat treatment it has a viscosity similar to many types of asphalt used in the paving industry. Although bio-oil showed very good high temperature performance, the same was not verified at low temperatures. Therefore, GTR from cryogenic milling was used to modify the bio-oil. Then, a blend was produced by adding 20% (w/w) of this bio-binder to a PG 64-22 asphalt. The resulting binder was aged, and the storage stability test (separation sensibility) was performed. The initial GTR, bio-oil, bio-binder, asphalt and resulting binder were tested by means of Fourier Transform Infrared Spectroscopy (FTIR) before and after aging. The Dynamic Shear Rheometer (DSR) was used to build the master curves of all the materials and the binders high temperature continuous performance grade was determined. Two mixes compacted for 4% and 7% air voids were studied in regard to water susceptibility, fatigue cracking, dynamic modulus, flow number and low temperature fracture resistance. The results showed that this binder can perform as well or better than conventional asphalts over a large range of temperatures.