The CSX intermodal terminal in Chicago uses giant cranes that run on large rubber wheels to transfer rail cars from one train to another. In the past, it has paved with asphalt and it didn’t take long for the heavy cranes to cause significant rutting. To eliminate the rutting, CSX’s paving engineer, TIGERBRAIN Engineering, proposed it pave 6,500 cubic yards of special lanes with Roller-Compacted Concrete (RCC) for the cranes to run on.

At the same time, NRMCA member Prairie Materials in Chicago had installed a portable ribbon mixer onto a dry batch portable ready mix plant shown here as part of an increasing effort to promote RCC in the Chicago area and, as a result, it was able to supply RCC to the CSX project. The portable ribbon mixer mixes 8 cubic yards of RCC in 30 seconds. For this job, Prairie mixed two separate 4.5 cy loads and placed them into a dump truck for delivery to the project site.

First, asphalt pavement was cut and removed to accommodate the new crane drive lanes. Then, 16 inches of RCC was placed in two lifts onto a compacted subgrade using two asphalt road wideners. Vibratory rollers compact the RCC after each lift. A tack coat was applied to the top surface of the RCC in preparation for two inches of asphalt wearing course. The whole process was done in a single day. Central Blacktop, an asphalt contractor, performed the delivery and installation of both the RCC and asphalt. CSX’s construction consultant, Kelleher Construction’s Dave Roethig, added that CSX has used this method in other terminals and is happy with the results.

"RCC is definitely the right solution for heavy duty applications and can compete with asphalt on a first cost basis," said Theron Tobolski of Prairie Materials. "We are working with engineers on an increasing basis to convert asphalt paving designs to RCC/asphalt designs. And by using a portable ribbon mixer, it allows us to supply RCC projects from almost any Prairie location."