Effect of used-tire-derived pyrolytic oil residue on the properties of polymer-modified asphalts

Polymer-modified asphalts are prepared by incorporating recycled polyethylene (RPE) and a used-tire-derived pyrolytic oil residue in asphalt. A thorough characterisation showed superior properties for the modified asphalts at high temperatures. Low temperature properties of the base asphalt were found to deteriorate after addition of polymer. The asphalts modified with 10% pyrolytic oil (H18) obtained by vacuum pyrolysis of used tires showed improved low temperature properties. Based on optical micrographs it was concluded that contribution of the Ostwald ripening mechanism to phase separation of the dispersed polymer phase is negligible. It was found that the RPE structure changes in the mixture do not depend on the type of asphalt. The SHRPʹs high temperature (TSHRP) criterion was found to correlate with the Ring and Ball temperature (TRB) with a systematic 20° difference between the two temperatures (TSHRP>TR&B). The asphalt mixtures containing 10% H18 and 1% polymer were found to have the best low and high temperature performance.