Equipment World Digital Magazine
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July 2017 | EquipmentWorld.com 50 practices. LCCAs do not address environmental issues or "livable community conditions" of a project, which FHWA cautions could be dif- ficult to determine or could "double count" what's also measured in an LCA. The agency prefers LCCAs be used as a tool to support project decisions, and it recommends its RealCost program in processing LCCA data. Sustainability rating systems list construction practices or features of a project that affect sustainability and measure the impact of these factors. "In its simplest form, a rating system may count the implementa- tion of every best practice equally (e.g., all worth one point), in which case the rating system amounts to a tally of the number of best prac- tices used," says the Pavement Life Cycle Assessment Framework. "In more complex forms, rating systems weight best practices (usually in re- lation to their impact on a selected definition of sustainability or a selected set of priorities), which can assist in choosing the most impact- ful best practices to use given a lim- ited scope or budget. Many national and international pavement sustain- ability rating systems are currently available (e.g., INVEST, Greenroads, and Envision)." Materials and sustainability Longevity is a sure test of a sustain- able pavement, and this measure is driven by the materials used, both recycled and new. Roughly 140 million tons of concrete is recycled each year in the United States, where more than 150,000 miles of highway are paved with concrete, according to the National Concrete Pavement Technology Center (CP Tech Cen- ter). Five percent of the 445 million cubic yards of ready mix concrete is returned to plants each year. Forty-four states allow recycled concrete aggregate (RCA) to be used in various applications. The majority of RCA, 65.5 percent, is used as aggregate in base, with 9.7 percent used in asphalt mixtures, 6.5 percent in concrete mixtures, 7.6 percent as fill and 3.2 percent as high-value rip rap. The CP Tech Center recently sur- veyed concrete pavement compa- nies about the use of RCA, offering a look at 26 contractor firms in 19 states. The firms represent about 18 percent of the national volume of concrete paving for 2014 through 1,063 projects. Fourteen of the firms outsource their recycling, while six did their own, and five did a combination of both. A little more than half reported that at least 81 percent of their projects included removal of pavement, which would then be recycled. Granular subbase was the most often cited use of RCA, at 42 percent. Another 16 percent reported RCA was crushed product for other markets, 15 percent was used for granular shoulder and other crushed products related to pavement, 14 percent went toward road technology | continued 2016 ACPA Excellence in Concrete Pavement Awards Silver Award win- ner in the Divided Highways (Rural) – I-69 in Indiana. Contractor: E&B Paving, Anderson, Indiana. (source: ACPA)