Evaluation of Open-Graded Friction Course Mixtures Containing Cellulose Fibers

Abstract

Open-graded friction courses (OGFCs) are special-purpose mixes used to improve friction, minimize hydroplaning, reduce splash and spray, improve night visibility, and lower pavement noise levels. OGFCs typically utilize a gap grading for aggregates and a low percentage of filler. The asphalt content for OGFCs is generally slightly higher than that for dense-graded mixes. The combination of uniform grading, low filler, and normal OGFC asphalt content can lead to the draining of asphalt binder from a mix (typically called draindown) during transportation and laydown procedures. States that use OGFC typically utilize fibers to help prevent draindown. Generally, these states have specified mineral fibers over organic fibers because of concern that organic fibers (cellulose) would absorb water and lead to moisture problems in the field. A study was conducted to evaluate the use of cellulose fibers in OGFC mixes. The study entailed both a field phase and a laboratory phase. Field work entailed conducting a visual distress survey of six experimental OGFC pavements placed in Georgia during 1992. These pavements contained six different combinations of binder polymer and additives. Laboratory work entailed preparing OGFC mixes with both cellulose and mineral fibers and performing numerous moisture sensitivity tests. Results indicated that cellulose fibers performed as well as mineral fibers in OGFC mixes.