Creep-Recovery Behavior of Asphalt Binders Modified with SBS and PPA: Fid-Bau Portal

Creep-Recovery Behavior of Asphalt Binders Modified with SBS and PPA

Domingos, M. D. I. / Faxina, A. L.

The main objective of this study was to investigate the impact of longer creep-recovery times on the percent recovery ( $R$ ) and the nonrecoverable compliance ( $J_{n r}$ ) of three asphalt cements (AC), or binders, modified with (1) styrene-butadiene-styrene (SBS) copolymer, (2) polyphosphoric acid (PPA), and (3) SBS+PPA. The base material is a $50 / 70$ pen-grade (PG 64-xx) asphalt binder and the modified asphalt binders have the same high-temperature performance grade (PG 76-xx). The impact of longer creep-recovery times was addressed by calculating the percent recovery and the nonrecoverable compliance ratios at the test temperatures of 70°C and 76°C. The multiple stress creep and recovery (MSCR) test was used to determine the $R$ and $J_{n r}$ values at the stress levels of 0.1 and 3.2 kPa. Two creep-recovery times were used, namely, $1 / 9$ and $2 / 18 s$ . The highest $R$ values and the lowest $J_{n r}$ values can be found in the AC+PPA formulation. The increase in both creep-recovery times caused less impact on the rutting susceptibility of the AC+SBS+PPA than the AC+SBS and the AC+PPA under the same MSCR test conditions.