Effect of organic fibers on open-graded friction course mixture properties

Open-graded friction course (OGFC) or porous asphalt mixtures are special mixes used for improving the surface friction, increasing surface permeability, and reducing pavement noise. The mix consists mostly of coarse size aggregate with little fines. This study was conducted to evaluate the effect of two types of organic fibers: date-palm fibers and textile fibers, in combination with styrene butadiene rubber (SBR) polymer on the properties of OGFC mixes. A total of six different mixes were evaluated. Mix designs were performed according to the design procedure proposed by the National Center of Asphalt Technology (NCAT) for a range of 4.5-6.5% asphalt content. One-way ANOVA using the Tukey method of multiple comparisons was used to test the effect of the modifier and/or stabilizer on abrasion as an indication of raveling potential as well as draindown. The results indicated that the asphalt mix containing date-palm fibers and SBR polymer at 5.0% and the asphalt mix containing textile fibers and SBR polymer at 6.5% asphalt content satisfied the mix design criteria. The asphalt mixes at optimum asphalt content were evaluated for moisture susceptibility using the indirect tensile strength.