Laboratory Evaluation of the Mechanical Properties of Asphalt Concrete Reinforced with Aramid Synthetic Fibers

The research project presented in this report evaluates the effects that the addition of aramid fibers has on the mechanical properties of a dense-graded mix frequently used in California, a Superpave mix with 19 mm (3/4 in.) nominal maximum aggregate size, 15 percent reclaimed asphalt pavement (RAP) content, and PG 64-10 binder. A fiber-reinforced asphalt concrete (FRAC) was prepared by adding aramid fibers at a rate of 0.013 percent of total mix weight. The mechanical properties of the two mixes, original and FRAC, were determined in the laboratory. Based on laboratory testing, adding the fibers improved fatigue resistance of the original mix at high strain levels considerably. It also improved rutting resistance while only changing the stiffness a little. The added fibers did not negatively impact the compactability of the mix nor did it seem to change the mix volumetrics. The laboratory testing results indicate that adding aramid fibers would be of greatest value where asphalt is subjected to high strain levels, such as in overlays of jointed concrete pavements or in pavements with considerable cracking. This study did not consider any occupational health risks, environmental risks or cost considerations, effects on constructability (particularly compaction) in the field, or what effects added fibers might have on the ability to recycle fiber-reinforced asphalt pavement.