Loop Link, Chicago

Anyone who’s ever commuted in downtown Chicago knows the nightmare it is to get from one point to the next. With buses making more than 1,000 daily trips across the Loop, it was time to invest in a plan to address the congestion while keeping pedestrians and cyclist safe. The $31.8 million Loop Link project will improve traffic flow with dedicated lanes for buses and cars, and protected lanes for bicyclists and pedestrians.

Prairie Material teamed up with Butterfield Color, project designer Alfred Benesch, the Chicago DOT, and concrete contractor Capitol Cement to develop a unique red mix that would delineate the bus-only concrete lanes on 14 blocks.

“Prairie performed three trial batches to get the look CDOT was after,” says Capitol Cement project manager Dan Melnyk, who is overseeing the 1,400-yard job.

Original mix specifications came from an exposed-aggregate mix, which included specialty red-granite coarse aggregate. “The proportions were not appropriate for a traditional finish,” says Prairie’s senior technical support rep Gary Hall, “so we had to significantly cut back the aggregate mass to make this mix more workable, finishable, and cost-effective.“

A high-early-strength requirement of 3,500 psi at three days was also factored in, says Hall, with red granite remaining in the mix to help maintain color integrity throughout the life of the concrete.

The entire project is scheduled for completion in 2016.