Better Roads Digital Magazine
Issue link: https://read.dmtmag.com/i/128531
Applications & Innovations by Tina Grady Barbaccia, Contributing Editor To avoid fracturing aggregates when compacting stone matrix asphalt (SMA) or open-graded mixes, it may be necessary to use two rollers set in low amplitude during the breakdown phase. Mix Optimization A formula for greenbacks and green roads W hen it comes to mix-design optimization, two goals stand out: dollars to be saved and how sustainable a road you can build. This means doing your homework and understanding calculations in mix design, explains Shane Buchanan, asphalt performance manager with Oldcastle Materials Group's Asphalt Performance Team. When designing a mix, it's important to conduct a quick review of mix volumetrics "to make sure you know what you think you know," he says. It also means, he adds, taking the time to ensure you are up to the current specifications in your area. "It goes back to being too busy," Buchanan points out. "You may not be aware of special provisions or specification changes. These could include changes from Departments of Transportation, a city or municipality, or even the Federal Aviation Administration. "Changes can open up the door to make a more economical mix," Buchanan says. "If you are not aware of that, you are losing at the beginning of the process." Specification changes aren't communicated as methodically as in the past when it resulted in a printed description in a specs book. "But with advancement of technology, specifications can change quite frequently," Buchanan says. "It's not always in printed form. This means you must constantly monitor an agency's website." Buchanan also recommends that operations get involved with their local asphalt or stone association. "A lot of time, they help work with the agency to change or create new specifications," he says. "It's very important that you stayed tuned into the process." For example, the use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) in mixes is growing Better Roads May 2013 35 A&I_BR0513.indd 35 4/29/13 9:23 PM