54 Stories of Pumped Lightweight Concrete

by Tom Morris, Hydraulic Press Brick Company

Prairie Materials (Votorantim – VCNA) of Chicago, IL was selected to provide approximately 14,000 cubic yards of steel fiber reinforced, 4000 psi lightweight concrete for a 742-foot, 54-story skyscraper located at 150 North Riverside, right on the Chicago River in downtown Chicago. The concrete mix called for the use of expanded shale, lightweight aggregate to achieve a maximum equilibrium density of 110 pounds per cubic foot. Pumping lightweight concrete this high requires a pumpable mix meeting the weight specification to achieve design dead-loads and to provide the optimum strength and fire rating to protect the building’s tenants and visitors. The mix also required good placement, workability and finishability characteristics to stay within the concrete construction’s allotted timeline.

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 entirety of the 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” slump, induced with a High Range Water Reducer to achieve a 9” 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” metal pump line in 4’ x 4’ solid concrete boxes, in four locations, to eliminate line vibration damage and potential costly downtime. A 5” 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 approximately 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.