As part of a 15-year, $12 billion capital program “Move Illinois: The Illinois Tollway Driving the Future,” the Illinois Tollway commissioned about 60 miles (96 km) of threelane- wide highway upgrades along the Jane Addams Memorial Tollway (I-90) between Rockford, IL, and Elgin, IL. I-90 was rebuilt and widened and concrete was selected to incorporate innovative technology to achieve sustainable development objectives. Specifications included an extensive new array of performance testing for submittals and encouraged use of non-portland-cement recycled cementitious materials components along with inclusion of recycled aggregates.
Slag cement was used in approximately 20 miles (32 km) for an innovative two-lift composite concrete pavement, as follows:
•Bottom/base lift: The lower lift (8.25 in. [209 mm]) was a “black-rock” mixture containing coarse fractionated recycled asphalt pavement (RAP) as 15% of the coarse aggregate. The mixture also contained 40% of slag cement with Type IL(10) cement; and
•Top lift (3 in. [76 mm] thick): The design was for an Illinois DOT PV mixture with 75% Type IL(10) portland limestone cement with 25% slag cement.
Both mixtures consistently provided required fresh and hardened concrete properties, enabling paving to progress without incident and on time. This was the first major use of two-lift paving in Illinois tollway construction, the first use of “black-rock” in a base lift for two-lift construction, the first use of ASTM C595/AASHTO M 240 Type IL portland limestone cement in Illinois highway and tollway construction, and the first extensive project application employing the new submittal system incorporating a broad range of performance testing.
Project credits: Illinois Tollway, Owner and Engineer; William Charles Construction and Curran Contracting, Primary Contractors; F.H. Paschen, S.N. Nielsen, Inc., and K-Five Construction Corp., Paving Contractors; Ozinga Ready Mix Concrete, Concrete; and Holcim (US), Inc., Slag Cement.