Construct - Issue 43

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The innovations used in developing the new materials have driven substantial carbon savings. The high RAP content resulted in a 23% reduction in carbon compared with traditional materials, while manufacturing the asphalt as a warm mix saved a further 14% as it only had to be heated to 150 o C. Standard hot mix asphalts are heated to 180 o C. As a result, the total carbon emissions for the mile long stretch of road equated to 118t, while the equivalent for a standard mix would be around 154t. FM Conway head of technical, aggregates and asphalt, Mark Flint, explains how these savings were achieved: “We approached it on two fronts: combining the fuel saving technology of mixing it cooler with the material saving aspect of using the RAP.

Highways’ net zero strategy target of a 40- 50% reduction by 2030.”

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FM Conway business development director Nick Burman highlights another positive aspect of using warm mix: “We completed it in just nine night shifts, saving three shifts compared with a conventional mix. “That provides customer benefits by reducing network occupation, as well as reducing risk because operatives spend less time on carriageways. “It also means we made even more carbon savings, because there were fewer vehicle emissions,” he adds. FM Conway head of carbon and environment Vanessa Hilton says: “Using RAP at this level requires a twin drum dryer asphalt plant and there are only seven of these currently in the UK, with FM Conway owning two of these plants.” u

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"The combined 37% carbon saving that we achieved brings the trial close to National

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