Investigation of usability of natural hemp fiber instead of cellulosic fiber in stone mastic asphalt

The demand for transportation on highways is increasing as the day goes on and in addition, the increase in traffic volume on highways causes various problems such as rutting. Stone mastic asphalt mixtures have been developed in order to prevent tire tracks, which is one of the most common deteriorations in pavements. Stone mastic asphalt mixtures has high grain contact and bitumen rate. In order to prevent the bitumen from leaching over the aggregate, cellulosic fiber, mineral fiber, plant-based fiber and various additives are used in stone mastic asphalt mixes with high bitumen rate. In this study, it is aimed to investigate the effect of the fibers obtained from the hemp plant on the draindown of stone mastic asphalt mixtures. In the first stage of the study, the optimum bitumen rate was determined by producing 18 samples with 5,0% 5,5% 6,0% 6,5% 7,0% 7,5% bitumen ratios with cellulosic fiber. In order to determine the effect of fiber additives on the draindown of asphalt, Schellenberger test was applied to blends containing 1, 2, 3, 4, 5‰ and fiber-free mixtures. In this study, samples were prepared with hemp fibers of 2, 3, 6, 12 mm lengths in order to determine the effects of hemp fiber length on stone mastic asphalt mixtures. In order to determine the effect of hemp fiber mixing ratio on the properties of stone mastic asphalt mixtures, samples were prepared with fiber additives at 1, 3, 4‰ ratios and without fiber. Dp, Vh, VMA, Vf, MS and flow values of samples prepared by Marshall Design Method were determined. Stone mastic asphalt mixtures containing natural hemp fiber as fiber were compared with samples containing cellulosic fiber of the same properties. As a result of the experimental results, it has been revealed that natural hemp fiber at 1, 2 and 3‰ ratios has a higher performance than cellulosic fiber in terms of draindown. Key Words: Stone Mastic Asphalt, Natural Hemp Fiber, Draindawn.