Dubbed the “The Guillotine,” this office building on the Chicago River is considered the city’s most dramatic design since Aqua Tower in 2009. Three-quarters of the two-acre site is devoted to public park space, so the foundation is unusually small for a 1.2 million-square-foot structure with 54 floors. The project required a lightweight, pumpable mix with excellent placement, workability, and finishability characteristics. Prairie Material, a Votorantim Cimentos company headquartered in Bridgeview, Ill., provided 14,000 cubic yards of 4,000 psi, steel-fiber-reinforced concrete. The mix used expanded shale aggregate to achieve a maximum equilibrium density of 110 pounds per cubic foot. The mix also required .

Colin Chiluski, Prairie’s QC Technician who conducted testing at the batch plant and jobsite said, “The pre-wetted lightweight aggregate concrete mix was very easy to work with; the concrete maintained its slump throughout the entire job, it pumped well even with the addition of steel fibers. It made my job easy.”

A Schwing stationary pump was employed to push a 9-inch slump, induced with a High Range Water Reducer to achieve a 9-inch slump, lightweight concrete mix up 54 stories. Knowing that pumping concrete that high could create excessive pump-line shock/vibration at the ground level, Meyer Pumping encased the ground level 5-foot metal pump line in 4 feet by 4 feet solid concrete boxes, in four locations, to eliminate line vibration damage and potential costly downtime. A 5-foot line system (metal line and rubber hose) was used throughout. Concrete Contractor, Trin Vega, said, “Through it all, we have actually had a very positive and productive experience. The lightweight concrete pumped, placed and finished very well; we finished ahead of schedule and we are completely satisfied with the overall experience. This will give Clark Construction, the project’s General Contractor, a cushion to help the finishing trades complete their work on time.”

Goettsch Partners, a Chicago based Architectural firm, designed the new 150 N. Riverside building with a LEED mindset. The 742-foot tower has a very narrow footprint due to the train tracks that striate the property. The project is a 54-story Class “A” office building with about 1.4 million rentable square feet. It is a LEED-CS Gold Pre-Certified building maximizing open space within the building. The building will also include a Green Roof design using expanded shale material used to open and enrich the planting soil.