Rutting on asphalt binders and mixtures modified with PPA and Elvaloy®: laboratory aspects and rheological modeling

There has been a lack of proper understanding about the actual rutting performance of asphalt binders/cements modified only with polyphosphoric acid (AC+PPA). Accordingly, this study aimed at evaluating the rutting resistance of the AC+PPA at typical Brazilian high pavement temperatures. Due to promising findings, another formulation with Elvaloy® and PPA (AC+Elvaloy+PPA) was also investigated. Standardized multiple stress creep and recovery tests were performed at 64 and 70°C, whereas the flow number (FN) was determined on dense-graded mixture samples and at 60°C. The AC+PPA (PG 76-22) and the AC+Elvaloy+PPA (PG 76-22) were based on a PG 64-22 original binder. The AC+Elvaloy+PPA could deal with heavier traffic levels and at both scales, as the nonrecoverable compliances were lower than 1.0 kPa-1 and FN exceeded 7,000 cycles. Conversely, the AC+PPA did not show the same pattern of behavior because FN was only 17% higher than the one of the original binder.