PERFORMANCE INVESTIGATION OF HOT- AND WARM- ASPHALT MIXTURES MODIFIED WITH SUPERPLAST

Moisture and stripping damages are the most prevalent cause of defects of both Hot-Mix Asphalt (HMA) and Warm-Mix Asphalt (WMA). Adhesion between aggregates and bitumen is a crucial factor that affects such defects. Various methods, such as incorporating additives, have strengthened the asphalt mixture's resistance to moisture and stripping. This paper aimed to experimentally investigate the effect of including a low-cost polymer additive (Superplast) into HMA and WMA mixtures. For this goal, a 60/70 penetration grade bitumen was used. For preparing the WMA mixtures, Showax was employed with percentages of 2, 3, 4, 5, and 6% by weight of bitumen. Polymer modified mixtures (HMA and WMA) were prepared by adding 3%, 4, and 5% of Superplast by weight of the binder. Performance characterizations of the unmodified and Superplast-modified mixtures include stiffness, moisture damage resistance, and bonding. These characteristics were evaluated via Marshall, Lottman, and Double Punching tests, respectively. Results revealed that incorporating Superplast improved the adhesion between bitumen and aggregates, which ultimately led to an increase in the stiffness and moisture resistance of both HMA and WMA. Moreover, Superplast-modified WMA mixtures exhibited the best moisture and stripping resistance performance compared to Superplast-modified HMA and other unmodified mixtures.