Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/506694
road's affect on its surrounding en- vironment, but also the working life of the road, often referred to as the use phase (see the sidebar Sustain- able Pavements Life Cycle). There are broad arguments about the impact of the use phase of a road. It does represent the longest segment of time when thinking of a road's lifecycle. "Contractors have been doing sus- tainable practices for a long time," says Leif Wathne, executive vice president of the American Concrete Pavement Association. "They either give them a competitive advantage or make them money. The sustain- able practices we trumpet make the material side of it more competitive. Conventionally, most people think of recycling materials, and these things are good, but this thought process is missing the biggest ele- ment – the use phase." Wathne compares just thinking about the materials on a road to just thinking about the water in plastic bottles. While the plastic waters are recycled, they also require a lot of plastic to be used and reused – vs. getting water from the tap in a container that doesn't have to be recycled, such as a glass bottle. "Green washed" is a phrase Wathne used to describe this perception. "It's a life cycle assessment atroc- ity," he says. "If we really want to focus on sustainability and change the busi- ness, design has a big role. The driver should be design," Wathne said "How we build and what we build with has an impact on the pavement world." While Dr. Heather Dylla, director of sustainable engineering for the Na- tional Asphalt Association, agrees that considering the use phase is impor- tant, she says it's a harder concept to solidify into quantifiable data. "Use phase is highly uncertain in all models, because for one thing main- tenance impacts use phase," Dylla says. "The materials still have a big impact on use phase, and it's easier to maintain a road that was built at a higher level of smoothness." "Sustainability is context specific," she adds. "The solution for one is different than another. We have to look at the relative balance and it's important that we're looking at this geographically." Her point is that the use phase on a road with 100,000 vehicles travelling over it May 2015 | EquipmentWorld.com 54 highway contractor | continued Sustainable pavements life cycle The Federal Highway Administra- tion (FHWA) says the key concepts for sustainable pavements include a bigger picture approach, in con- sidering the environmental, social, and economic factors at play. It's vital to have a holistic approach to the entire life of a pavement, and adjust practices and methodolo- gies to a pavement's application. There are six phases of a sustainable pavement life cycle generally recognized, and each has a set of best practices. These phases include: Materials production – For sus- tainable pavements, this includes, for example, cutting back on the amount of virgin material in a project by using recycled materials or reclaimed pavement. Design – A life cycle assessment or sustainability ratings must be incorporated into the design from the very beginning. Construction – This phase covers the quality of the work and the impact on the surrounding envi- ronment during construction, much like Jackson mentions in the Iowa countryside. Use – The longest phase of a pavement life cycle, beginning once construction ends. Design has a major impact on this phase. Preservation, maintenance, and rehabilitation – Simply put, this is taking care of the pavement in a way that uses pavement pres- ervation methods that lengthen the usefulness of the road and keeps the pavement smooth. End-of-life – This is the handling of the materials when a road is being redone, so a deep consider- ation of how to best use the old pavement, such as being recycled back into new roadwork. This of course leads back to materials production. Optimized aggregate mix being placed in front of a paver for a Federal Highway Administration Highways for LIFE project in Texas.