A laboratory investigation of high polymer modified asphalt mixtures with softening agent

This study was initiated to evaluate the impact of aging and High Polymer Modified Asphalt (HPMA) binders containing a bio-based-oil softening agent (SA) on the rutting, cracking, and durability of asphalt mixtures. One control asphalt binder (PG 52-34), Styrene-Butadiene-Styrene (SBS) polymer modifier, and corn-oil SA were used to produce four asphalt mixtures including a control prepared using PG 52-34 binder and three modified mixtures were produced by blending PG 52-34 binder with different dosages of SBS and SA. The mixtures were tested using the Dynamic Complex Modulus (|E*|), Hamburg Wheel Tracking Device (HWTD), Flow Number (FN), Indirect Tension Cracking Test (IDEAL-CT), Semi-Circular Bend (SCB), Disk-Shaped Compact Tension (DCT), and Cantabro Durability tests. The impact of aging on cracking resistance was also evaluated by subjecting all mixes to short-, long, and extended-long-term aging levels. The Analysis of Variance (ANOVA) and post-hoc statistical analysis were also performed on the testing results. Based on testing results, SBS and corn oil SA increased the durability and rutting resistance of asphalt mixtures. At extreme low-temperature (i.e., -24°C), the use of SBS and corn oil SA improved the cracking resistance of asphalt mixtures; however, increasing the SBS and/or the SA dosage rates had a negative impact on their cracking resistance. Using balanced dosages (i.e., 7.5% and 7%) of SBS and corn oil SA led to the best improvement in durability, rutting, and short-term cracking performance