Granite recently joined the Sustainability Infrastructure Advisory Board (SIAB) at Harvard University.

This board – with other members such as the Louis Berger Group, HNTB and Stantec, provides input to the Institute for Sustainable Infrastructure (ISI) there, developers of the new infrastructure rating system, Envision, developed to help designers, builders and infrastructure owners build and direct infrastructure projects toward increasing levels of sustainability.

More information on Envision can be found in last month’s RoadScience article.

Landmark Colas Study

Paving the way for these calculators was a landmark 2003 report. Environmental Road of the Future: Life Cycle Analysis, Energy Consumption and Greenhouse Gas Emissions, by M. Chappat and J. Bilal – was released by the Colas Group and is an in-depth analysis of energy consumption and GHG emissions of more than 20 different paving product types by ton of material placed.

Chappat and Bilal show that portland cement concrete (PCC) paving materials and processes demand the most energy, followed by hot mix asphalt (HMA) paving. The report also showed that cold-in-place (CIP) recycling is the least energy-intensive process.

“A comprehensive and realistic measure of energy use and GHG emissions of a specific type of roadwork begins at the extraction of raw materials from the earth, including all intermediate steps, such as transport, refining, manufacturing, mixing and placement,” says Jim Chehovits, P.E., vice president, operations, Crafco, Inc., and Larry Galehouse, P.E., director, National Center for Pavement Preservation. “These energy input and emissions data then can be extended via an annualized life extension basis.”

Energy consumption for aggregate production includes quarrying, hauling, crushing and screening. Chappat and Bilal demonstrate that energy consumption for aggregate production ranges from 25,850 to 34,470 Btu/t, and GHG emissions range from 5 to 20 pounds CO2/t.

Energy consumption for asphalt binder production includes crude oil extraction, transport and refining. Energy consumption for asphalt binders has been determined to be 4.2 mm Btu/t, and GHG emissions are 570 pounds CO2/t.

Download the report at www.colas.com/FRONT/COLAS/upload/com/pdf/route-future-english.pdf