Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/351731
AGGREGATES MANAGER August 2014 14 Other aggregates As the FHWA started its examination of high-friction surfacing as a safety coun- termeasure, there was a strong effort initiated to find domestic aggregates that provided friction numbers and polishing resistance similar to refractory grade cal- cined bauxite. The FHWA's Office of Pavement Tech- nologies' Surface Enhancements at Hori- zontal Curves (SEAHC) project funded the installation of demonstration projects throughout the country. In addition, the National Center for Asphalt Technology conducted a side-by-side evaluation of eight aggregates (calcined bauxite, flint, granite, basalt, silica, taconite, emery, and coal slag). The results confirmed that refractory-grade calcined bauxite is the most durable and retains highest friction numbers. There may be opportunities, however, to use certain local aggregates that provide high initial friction numbers at locations with low traffic volumes. Cost/benefit There have been a number of cost/ben- efit evaluations conducted on the use of high-friction surfacing. Some evaluators attempt to compare it to other friction improvement options. Others push for the use of lesser aggregates, citing cost reduc- tions. The bottom-line is that high-friction surfacing using calcined bauxite should be compared with the cost of engineering reconstruction, not against other fric- tion materials. When compared with the cost of redesigning and straightening a horizontal curve, high-friction surfacing is a quick, low-impact solution. Unlike reconstruction, there are no environmen- tal impact studies and no long periods in which the roadway is taken out or pro- vides reduced service. No land purchases or other expensive measures need to be addressed. Instead of years of delay, high- friction surfacing provides agencies with a relatively low-cost and quick solution to make roadways safer. Information ATSSA has developed a website contain- ing information about high-friction surfac- ing. The website, www.highfrictionsurface. net, contains updates on research, speci- fications, press coverage of high friction surfacing, case studies, and publications. The frequently asked questions section has videos from industry leaders answer- ing questions related to installation and testing. Future The effort to find low-cost, systemic meth- ods to make roadways safer continues. In addition to high-friction surfacing, the use of colorized aggregates and binders will soon be in wide use to designate bicycle lanes (green), transit lanes (red), and electronic toll lanes (purple). The push by agencies to find ways to use local aggre- gates for some of these systemic solutions should provide new use for a variety of traditional aggregates. The time for mate- rial suppliers to get educated and monitor the potential for these new markets has arrived. AM Robert N. Dingess is the president of Freder- icksburg, Va.-based Mercer Strategic Alliance, Inc. and serves as chair of ATSSA's High- Friction Surfacing Council. The National Center for Asphalt Technology conducted a side-by-side tests of eight aggregates (calcined bauxite, flint, granite, basalt, silica, taconite, emery, and coal slag). While calcined bauxite was the most durable and retained the highest friction numbers, there may be opportunities for local aggregates that provide high initial friction numbers at locations with low traffic volumes. MARKETING