IDOT focuses on sustainable highway construction

The Illinois Department of Transportation supports green and other sustainable programs throughout the transportation industry. One effort is adoption of sustainable design and construction techniques, including use of recyclable and environmentally friendly materials when possible.

One specific goal of IDOT is to reduce its carbon footprint and achieve cost savings through the use of recycled materials in construction projects. A recently published summary of these efforts is available on ICT’s website (Illinois Highway Materials Sustainability Efforts of 2013). Accomplishments highlighted in the report include the following:

• In 2013, reclaimed and recycled materials totaling more than 1.7 million tons were used in Illinois highways. On a tons per mile basis, the amount of recycled materials used in 2013 was nearly four times the amount used in 2009.
• More than 80,000 tons of fly ash and 15,000 tons of ground granulated blast furnace slag were used to replace cement, which is a carbon-intensive material, in concrete.
• In 2013, nearly 40,000 tons of shingles were used in hot-mix asphalt—a 221% increase over 2012 quantities.
• In 2012, IDOT initiated an effort to develop a total recycle asphalt (TRA) mix that could be supplied with approximately 97% recycled material. The mix does not use any newly mined material and relies on slag and recycled concrete materials for aggregate, along with recycled asphalt pavement and recycled asphalt shingles. IDOT has constructed three demonstration projects that use TRA and is monitoring their performance over time.
• IDOT has taken steps to increase its sustainability efforts by modifying the cooperative research agreement with ICT and the University of Illinois at Urbana-Champaign to focus more on sustainability issues.