The widening and rebuild of the Jane Addams Memorial Tollway (I-90) in the northern part of Illinois in suburban Chicago, USA is a massive concrete recycling job (reported in American Concrete Institute’s (ACI’s) recent newsletter). The “The Jane Addams Memorial Tollway Website” touts it as “a 21st-century, state-of-the-art corridor linking Rockford to O’Hare International Airport”. The tollway is part of Interstate 90—the longest interstate in the United States, and covers 124 km (77 miles)—extending from near the Wisconsin border to the Kennedy Expressway. The I-90 corridor from downtown Chicago to Rockford serves nearly one million travelers per day.
The Tollway is committed to “Building Green” and minimizing the environmental impact of construction by reducing, recycling and reusing materials. “Our efforts are focused on minimizing the environmental impacts associated with our road building,” said Paul Kovacs Tollway Chief Engineer.
Recycling and reusing the existing concrete and asphalt as a base material for the new road bed with the help of a mobile crusher. “It’s a unique and fantastic way of keeping the existing materials on site and turning them into the proper size so they can be reused again,” Kovacs said. The tollway roads are built with concrete and shoulders and resurfacing are asphalt. Concrete pavements will include recycled asphalt aggregate along with supplemental cements, such as fly ash and ground blast furnace steel slag from industrial waste—reducing energy consumption and greenhouse gases. The roadway base and shoulders will include recycled asphalt pavement, recycled asphalt shingles and warm-mix asphalt. Recycled asphalt comprises about 33% of the new asphalt laid on the mainline and about 50 % of material used for the shoulder.The agency has used its I-90 rebuild as a laboratory to test mixing old asphalt shingles and pavement with new.
In addition to reducing the cost of this work, reuse of these materials reduces the need for virgin materials and reduces the volume of material that would otherwise be sent to landfills. Kovacs said that recycling and reusing is a very good environmental approach to road-building and saves a lot of money, adding the agency has saved about $200 million since 2006. “We don’t have to buy the new materials, we don’t have to haul in new materials and remove old materials, and we don’t have to pay any (landfill) disposal fees.”
The Project Steps: The project was begun by breaking up the existing concrete pavement into large chunks. The material was then mounded separately in the rows of I-90. Mile by mile as the roadwork moved east, a backhoe loaded the pieces of concrete into the mobile crusher’s feeder where they are pulverized into 4-by-6-inch chunks and whisked onto a conveyor belt that spits the finished product onto the road bed, making for a solid base. A layer of recycled, ground-up asphalt follows later, then three inches of warm asphalt.
“After we have a stabilized base, we build a new concrete layer on top to create this … sandwich,” Kovacs said. “The new concrete pavement is typically 33 cm (13 inches) thick.” The depth of concrete is tailored to the type of traffic, adding the thickest layer where truck traffic is heaviest, such as on the Central Tri-State Tollway.
Other Aspects of the Tollway Green Building:
- Energy efficient light emitting diode (LED) lights along the throughout the I-90 corridor to reduce energy consumption and maintenance when compared to conventional high-pressure sodium (HPS) lighting.
- undertaking projects that will protect and restore native prairie, forested fen and wetlands as part of the Tollway’s wetland mitigation efforts.
- 40 acres of new stormwater detention and a stormwater treatment train system that consists of approximately 54 miles of bioswales to help filter out sediments and pollutants associated with roadway runoff and minimize the potential for downstream flooding.
- New Illinois Route 47 Interchange (opened in November 2013) features several new green construction initiatives:
1. Geothermal water piping system (uses the earth’s natural heating and cooling abilities to help heat and cool nearby plaza buildings=cost-effective and sustainability
2. Reflective roofs and trellised vegetation for plaza buildings to further reduce heating and cooling costs
3. Ramp shoulder pavement that will allow water to seep through and reduce stormwater runoff.
The final stretch of the Jane Addams revamp should wrap up by the end of 2016.
Photos:
Home page: I-90 Western Segment concrete chunks before pulverizing; Above: Westbound concrete Pour; Link to Photos and additional photos: http://www.illinoistollway.com/news-room/photos-graphics/construction
For the I-90 Corrider Overview link, please go to: http://www.illinoistollway.com/construction-and-planning/projects-by-roadway/jane-addams-memorial-tollway-i-90/i-90-corridor-overview
For the Jane Addams Building the Tollway document, please go to: http://www.illinoistollway.com/documents/10157/b5dcfa1c-52d8-4e64-b6b9-5f0fc602b088
For the Daily Herald online article titled, “Tollway’s ‘mother ship’ chews up concrete, spits out savings on I-90″, please go to: http://www.dailyherald.com/article/20160815/news/160819486/