Asphalt is the pavement of choice for sustainability.
Asphalt is 100 percent reusable and recycled at a higher rate than any other material in America — including soda cans and newspaper. In fact, 94 percent of asphalt reclaimed from old roads and parking lots goes back into new pavements.1 When an asphalt pavement is maintained, the in-place material removed from the site becomes part of the raw materials for new pavement layers. A 100 percent reusable material, reclaimed asphalt pavements (RAP) perform as well or better than virgin mixes. In 2019, more than 97 million tons of RAP and 921,000 tons of reclaimed asphalt shingles (RAS) were used in new asphalt pavement mixes in the U.S. That year about 139 million tons of RAP and RAS were stockpiled for future use across the country. Reusing RAP in future pavements saved nearly 60 million cubic yards of landfill space during 2019.1
Fewer Greenhouse Gases
Asphalt pavements require less energy2 to produce and their production generates less material waste3 than other paving materials, and its production emits fewer greenhouse gases than concrete pavement.4 In fact, the asphalt binder used to make asphalt pavements is a byproduct of fossil fuels that were never burned and used as energy, such as diesel fuel or gasoline. Thus, the inherent CO2 is never released into the atmosphere.
According to the U.S. Environmental Protection Agency (EPA), 99.6 percent of the carbon in asphalt binder is stored instead of contributing to greenhouse gases.5 Not only are asphalt pavements a very effective means of sequestering carbon, the production of liquid asphalt from the heaviest fraction of a barrel of oil is much less energy intensive than trying to convert it to a fuel for energy use.6
To further reduce our environmental footprint, the asphalt industry continues to make great strides in the use of warm-mix asphalt (WMA) production. WMA technologies reduce the production and placement temperature of asphalt pavement mixtures by 30°F to 120°F.7 This lowers fuel consumption further and cuts greenhouse gas emissions.
On average, contractors report energy savings of almost 25 percent during warm-mix production. When WMA is fully implemented across the industry, the U.S. will save an estimated 150 million gallons of No. 2 fuel oil per year, while also slashing carbon dioxide emissions by an equivalent of 210,000 cars annually.8
The use of warm-mix asphalt grows each year. The estimated total tonnage of asphalt pavement mixtures produced at reduced temperatures with WMA technologies for the 2017 construction season was about 147.4 million tons.1 This was a 26 percent increase from the estimated 116.8 million tons of WMA in 2016, driven largely by increased WMA tonnage in the commercial, residential, and DOT sectors.1
Full-depth porous asphalt has shown to help filter water to keep pollutants out of the environment.9,10 These pavement structures, used mostly for parking lots, allow water to drain through the pavement surface into a stone recharge bed and infiltrate into the soils below the pavement. By replenishing water tables and aquifers rather than forcing rainfall into storm sewers, porous asphalt also helps to reduce demands on storm sewer systems. In areas where stormwater impact fees are imposed by local governments, such fees may be reduced by using porous asphalt.
Reduced Fuel Consumption
A smooth roadway not only provides drivers with peace of mind, it also increases vehicle fuel efficiency. Contrary to some recent claims that pavement rigidity is a major contributing factor to vehicle fuel economy, the FHWA WesTrack Tests quantified the relationship between smooth pavements and improved fuel economy. Smoother pavements lead to lower fuel consumption — 4.5 percent lower in the WesTrack Tests.11
While manufacturers make strides to improve an automobile’s fuel economy, transportation agencies, researchers, and engineers are concurrently working to refine and build smooth roadways that do the same. All told, Americans burn 175 billion gallons of fuel driving approximately 3 trillion miles a year. If roads across the nation were smoother and maintained in good condition, approximately 4 percent of the fuel consumed could be saved, reducing annual vehicle fuel consumption by about 7 billion gallons — the equivalent of taking more than 10 million vehicles off the road every year.11
- Williams, B.A., Willis, Richard & Shacat, Joseph (2019). Asphalt Pavement Industry Survey on Recycled Materials adn Warm-Mix Asphalt Usage: 2018 (IS 138) National Asphalt Pavement Association, Greenbelt, Maryland.
- Chappat, M. and J. Bilal (2003). The Environmental Road of the Future: Life-Cycle Analysis (French report: La Route Écologique du Futur: Analyse du Cycle de Vie). Colas Group. Boulogne-Billancourt, France. 3
- Gambatese, J., and S. Rajendran (2005). Sustainable Roadway Construction: Energy Consumption and Material Waste Generation of Roadways. Construction Research Congress 2005: pp. 1–13.
- Mahasenan, N., S. Smith, K. Humphreys (2003). The Cement Industry and Global Climate Change: Current and Potential Future Cement Industry CO2 Emissions. In Proceedings of the 6th International Conference on Greenhouse Gas Control Technologies (J. Gale and Y. Kaya eds.), Vol. 2, pp. 995–1,000.
- EPA (2014). Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2012. U.S. Environmental Protection Agency. Washington, D.C.
- Pellegrino, J., S. Brueske, T. Carole, and H. Andres (2007). Energy and Environmental Profile of the U.S. Petroleum Refining Industry. Energetics Inc. Columbia, Maryland.
- FHWA (2013). Every Day Counts: Warm Mix Asphalt. Federal Highway Administration. Washington, D.C.
- NAPA (2008). Warm-Mix Asphalt (PS-30). National Asphalt Pavement Association. Lanham, Maryland.
- Roseen, R.M., T.P. Ballestero, J.J. Houle, J.F. Briggs, and K.M. Houle (2012). Water Quality and Hydrologic Performance of a Porous Asphalt Pavement as a Storm-Water Treatment Strategy in a Cold Climate. Journal of Environmental Engineering, Vol. 138, No. 1, pp. 81–89.
- Zhao, Y. and C. Zhao (2014). Lead and Zinc Removal With Storage Period in Porous Asphalt Pavement. WaterSA, Vol. 40, No. 1, pp. 65–72.
- Sime, M., S.C. Ashmore, and S. Alavi (2000). Tech Brief: WesTrack Track Roughness, Fuel Consumption, and Maintenance Costs (FHWA-RD-00-052). Federal Highway Administration, McLean, Virginia.