Aramid Fibers in SC

Adding aramid fibers have suddenly become a very common practice for SCDOT to specify in select projects across SC. The past year so we have seen several projects have an Aramid Fiber Special Provision included in contracts or a change order may have been permitted to adopt the use the fibers in lieu of doing full depth asphalt reclamation in selected locations. The current reasoning behind using these fibers is to improve the overall strength of the asphalt mixture and provide increased benefit of cracking resistance, which can be very similar to adding PMA (Polymer Modified Asphalt).  SCDOT has mostly specified a double dose of fibers at 4.2 ounces per mix ton of pure fiber vs. a single dose at only 2.1 ounces per ton. It should be noted that the doses shown above are pure fiber without the addition of other dispersion aides added by the manufacturers (i.e. - polyolefin fiber and wax), and it is very important to discuss this with the two major suppliers (both associate members of SCAPA).  Metering the fibers has become very easy in the last several years with the manufacturers offering mobile trailers with the necessary metering devices enclosed and ready to hook to your asphalt plant. Data collection has become easy to verify the dosage rates with downloadable files to a PC, SD Card, or USB thumb drive that can be shared with QC personnel and SCDOT. Cliff Selkinghaus, SCAPAs Technical Director has made several visits this Summer to various asphalt plants and jobs that were running fibers to SCDOT jobs. He has observed very little issues with the metering of the fibers and virtually no issues have been noticed in the field during placement operations. Often its somewhat difficult to see the fibers unless you really look at the mix up close, the fibers resemble fine particles like human hair that attach to one another and can create a small string of fiber that reinforce the matrix of the mixture. Long term field performance will be the true indicator of success here in SC. Numerous projects have been constructed statewide and will continue over the next year, and we have seen an increase of the number of private customers that are now asking to use the fibers on their commercial projects, the forecast is looking bright and we are likely to see more reinforced asphalt mixtures in the future.