Evaluation of Warm-Mix and Rubber-Modified Open-Graded Friction Course Test Sections Made without Fibers in South Carolina

This paper summarizes the performance of open-graded friction course (OGFC) mixtures used to construct two experimental pavement test sections in South Carolina. The study's main objective was to evaluate OGFC mixtures made without fibers. One test section consisted of three OGFC mixtures [control with cellulose fibers, ground tire rubber modified without fibers, and warm-mix asphalt (WMA) without fibers], and the second consisted of two OGFC mixtures (control with cellulose fibers and WMA without fibers). Material was sampled from the asphalt plant during production. Tests were conducted on the fresh mix as well as specimens compacted at the plant and after reheating in the research lab. Results showed that the removal of fibers from the OGFC mixtures in both projects did not have any detrimental effects on the mix performance (drain down, permeability, abrasion resistance, indirect tensile strength, and fatigue resistance). The WMA mixture made with Evotherm exhibited increased fatigue resistance compared with the control mixture even though the WMA mixture did not contain cellulose fibers. In addition, the WMA mixture showed the potential to reduce heat loss resulting from the startup of the paving operation (i.e., running asphalt mix through a cold material transfer vehicle and then a cold paver). Limiting heat loss could improve the consistency of the OGFC mat density from the beginning transverse cold joint and thus potentially enhance the pavement performance.