Intrinsic adhesive and cohesive assessment of the moisture sensitivity of bio-rejuvenated recycled asphalt binders

Alternative binders not derived from fossil fuels, known as biobinders, are opening new paths for multiple applications in road infrastructure. Biobinders, usually produced from bio-oils obtained from the processing of biomass and industry by-products, are tuneable materials whose properties can be adjusted to meet specific targets. For this reason, an interesting approach is to couple biobinders with Reclaimed Asphalt (RA) by taking advantage of their rejuvenating properties to design bio-asphalt mixtures with high-content RA and no additional virgin bitumen. Recent research has proven the feasibility of this approach through validation at full-scale (BioRePavation project). However certain aspects related to the durability of bio-asphalt mixtures still require further research, one of these being their resistance to moisture damage. This study aims at filling some of these current gaps by conducting an initial investigation of the moisture sensitivity of selected biobinders and bio-rejuvenated asphalt binders. In order to do this, the intrinsic adhesion and cohesion properties of an extracted RA binder, two biobinders, their blends and two types of aggregates were characterised by means of Surface Free Energy (SFE), individually and as a system. The binders/blends-aggregate systems were further tested by means of the Pneumatic Adhesion Tensile Test Instrument (PATTI) to determine their pull-off tensile strength (POTS). The results show that the bio-rejuvenated asphalt binders present equivalent cohesive and adhesive properties to a conventional bitumen and superior performance when compared to the RA binder. Hence, the combination of biobinders and RA has great potential to guarantee resistance to moisture damage of bio-recycled asphalt mixtures with high-content RA and no additional bitumen.