With Foundation Poured, 150 N Riverside is Ready to Rise

By Curbed Staff Feb 17, 2015, 12:30pm CST

As nature sent us a very cold shoulder this Valentine's Day, many of us enjoyed the warmth of the indoors. However, at 150 North Riverside, crews worked in the frigid temperatures from Friday evening through all of Saturday to complete the foundation mat for the future 54 story tower. A foundation mat is a structural piece that ties all of the subterranean elements of the foundation together, spreading the loads of the future office tower between them. All of the drilled caissons have their respective tops tied into the mat, which is a very large block of reinforced concrete that must be poured all at once.

So, how large is this foundation in particular? According to one of the highrise enthusiasts over at SkyscraperPage Forum, the mat is 162 feet long, 47 feet wide and 10 feet deep, equating to over 2800 cubic yards of volume. It's suggested that 3600 cubic yards of concrete was used in the total pouring operation for 150 N Riverside. While mat pours are standard for larger buildings completing foundation work, this one is particularly large for a tower of this size. This could be due largely to how the unconventional cantilevering design of this building places immense structural loads onto the core which then rests atop of the foundation mat and the caissons below. Pre-cast concrete beams known as bulb tees will span the railroad tracks to support the new riverfront park.

Crews at 150 North Riverside used two mobile concrete pumps at the same time, one staged on Randolph Street and the other on Lake Street. Each pump received two truck loads of concrete at once while other trucks staged nearby to keep the flow moving in a carefully orchestrated pattern, think of it as something like a ballet of heavy equipment. Concrete steamed in the cold temperatures as it left the trucks which also had icicles dangling from the vehicle frames. Crews used flexible booms and piping to adjust the flow of concrete into the cage of steel reinforcing bars while the mat was filled. After a sufficient amount of curing has been reached, we can expect to see this tower begin reaching for the sky.