Expanding and improving the 20.6 miles of the I-90 Illinois Tollway from Rockford to O’Hare International Airport in 2014 was a massive project with a price tag of $2.5 billion. Despite the political sensitivity of the project, or perhaps because of it, the concrete mixes combined multiple innovative materials to result in a durable yet sustainable mix. Ozinga Ready Mix Concrete, Chicago, was the primary concrete producer on the project.

To control costs while maintaining the highest quality, the pavement was placed as a two-lift composite:

  • The lower/base lift, 8.25 inches thick, was a “black-rock” mix containing coarse fractionated RAP (recycled asphalt pavement) as 15% of the coarse aggregate. The mix also contained 40% slag cement as part of the cementitious material.
  • The top 3-inch-thick lift was an Illinois DOT PV mix with 75% Type IL(10) portland-limestone cement with 25% slag cement.

The concretes followed Illinois Tollway requirements regarding extensive laboratory evaluation. The portland-limestone cement was a Type IL(10), with the (10) meaning it contained 10% finely divided limestone, per AASHTO M240/ASTM C595 nomenclature. The specific product, provided by Holcim, was manufactured to match the performance of the Type I/II low-alkali portland cement that was used in some other portions of the work.

Overall, there were four paving contractors on the project: K-Five Construction, FH Paschen/SN Nielsen, Plote Construction, and R.W. Dunteman. The primary contractor for the K-Five contract was Curran Contracting, and Paschen was a subcontractor to William Charles Construction on one contract.

Two firsts

The project incorporated two unique firsts for the Illinois DOT:

  • The first use of AASHTO M240 Type IL portland-limestone cement concrete, and
  • The first extensive use of two-lift paving, with the more wear-resistant course cast for the top 3 inches of the 11¼-inch-thick pavement.

The Illinois Tollway is a revenue bond-financed administrative agency of the State of Illinois that is solely funded by user-fee and concession revenue. As part of a 15-year, $12 billion capital program — Move Illinois: The Illinois Tollway Driving the Future — for construction in 2014 the Illinois Tollway commissioned about sixty eastbound lineal miles of three-lane-wide highway upgrades along the Jane Addams Memorial Tollway (I-90) between Rockford and Elgin, rebuilding and widening the tollway into a state-of-the-art 21st century corridor.

There were seven contracts for the combined westbound mainline work, divided among the four contractors. All told, about 325,000 cubic yards of concrete was needed. Of this, a significant portion used concrete containing Type IL portland cement. The Illinois Tollway’s use of the Type IL cement adds onto the innovation that the Tollway has brought to Illinois pavements. The Tollway’s research into the use of “black rock” (the coarse portion of fractionated reclaimed asphalt pavement – FRAP) allowed it to incorporate recycled aggregate into the Rockford-to-Elgin portion of the I-90 reconstruction. The “black rock” mix was incorporated into the two-lift concrete construction, where the two lifts were placed “wet-on-wet,” with the black-rock mix covered by a typical paving mix containing no recycled aggregate.

Three PLC contracts

For the concrete containing Type IL(10) cement, there were two 8-mile-long contracts and one 4-mile long-contract, totaling 20.6 lineal miles of three-lane-wide mainline paving. All of the Type IL(10) cement concrete pavement was 11¼-in. thick. FH Paschen/SN Nielsen paved two contracts; K-Five Construction paved one contract.

K-Five Construction paved 52,500 cubic yards of the concrete, and FH Paschen/SN Nielsen paved 105,000 cubic yards. Also, for all three Type IL(10)-cement contracts, 21,000 cubic yards were cast in barrier-wall base concrete, and 30,000 cubic yards were cast in the barrier walls.

“The Jane Addams Memorial Tollway connects two of Illinois’ largest metropolitan areas, and this project will improve the lives of millions of motorists who use it every year,” said Illinois Governor Pat Quinn. “This infrastructure investment will modernize one of our most important interstates, put thousands of people to work, and lay the foundation for economic growth for decades to come.”

Mark Luther is the senior technical services engineer for Holcim US in St. Louis.

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