Evaluation of bonding between reclaimed asphalt aggregate and bitumen emulsion composites

The bond strength between bituminous binder and aggregate is fundamental to evaluate the performance and durability of cold bitumen emulsion mixtures (CBEM). The interaction developed at binder-aggregate interface is strongly dependent on the properties of aggregate, residual bitumen and emulsifiers, as well as on the environmental conditions affecting emulsion breaking. When reclaimed asphalt (RA) aggregate is used in the production of CBEM, the adhesion issue becomes more complex because the residual bitumen interacts with the aged bitumen film coating the RA aggregate surface. In this research, the binder bond strength (BBS) test was performed to evaluate the bonding between a bitumen emulsion, a cold mastic prepared using limestone filler and artificial RA substrates produced using two aggregate sources. The moisture sensitivity along with the effect of curing temperature and time on the bond strength development were also evaluated. The results showed good affinity between both cold bitumen emulsion composites and the aged bitumen film coating the RA substrate, also highlighting a reduced moisture sensitivity for most of the tested systems. Moreover, the BBS results allowed to properly discriminate the effect of curing temperature and time on bond strength between the artificial RA aggregate and the cold bitumen emulsion composites.