Experimental investigation of the use of waste paper cups in stone mastic asphalt mixtures

Today, due to increasing traffic density and axle loads, the use of Stone Mastic Asphalt (TMA) is becoming more common. SMA provides high durability and strong resistance to deformation. Because of its design, SMA mixtures have a high void ratio. This results in higher bitumen content compared to traditional asphalt and can cause bitumen separation from the aggregate. To prevent this issue, mineral fiber, cellulose fiber, and similar additives are used in SMA pavements. This study experimentally investigates the usability of waste paper cup (AKB) fibers in SMA mixtures. It examines their effects on bitumen percolation, moisture damage resistance, surface texture, and Marshall properties. Replacing commonly used cellulose fiber (SF) with AKB fiber offers innovation in both environmental sustainability and material performance. For this purpose, a gradation curve was determined within the limits of the Turkish Highways Technical Specification (KTŞ, 2013). The bitumen used was produced at the Aliağa refinery and has a penetration grade of 50/70. The study used PG 70-16 type Polymer Modified Bitumen (PMB), modified with Elvaloy RET (1.6%) and Polyphosphoric Acid (PPA, 0.2%). Fifteen samples were prepared with 5.0%, 5.5%, 6.0%, 6.5%, and 7.0% PMB ratios, including 0.35% cellulose fiber (SF). The optimum bitumen content (OBC) was determined. Then, SMA samples were prepared using WPC fibers instead of SF at different ratios (0.15%, 0.25%, 0.35%, and 0.45%) as well as fiber-free (0% NF) samples. Each AKB fiber ratio was tested with 5.0% to 7.0% bitumen content, and OBC was determined using the Marshall method. Indirect tensile strength (ITS), moisture damage (TSR), Schellenberger bitumen percolation, and sand patch tests were conducted on SMA samples. The results showed the effects of WPC fibers on ITS, TSR, bitumen percolation, and surface texture depth.