Carnegie Mellon University Tepper Quadrangle Concrete

Located on the urban campus of Carnegie Mellon University (CMU), the new Tepper Quad project involved construction of a 300,000-sf building, an underground parking garage and loading dock all built into the side of a hill. In 2014, CMU selected PJ Dick to build the new business school building, which featured the largest building project in North America to employ “Bubble Deck” technology.  The project is a structural cast-in-place building with six main levels and three below-ground levels to house mechanical systems. Approximately 25,000 cy of concrete was poured on the site, a challenging task as the building is situated on a typical Pittsburgh site featuring hilly terrain that positions the building entrances on different elevations. For example, the loading dock enters on a lower level street that is 40 feet down from the lower garage level.

PJ Dick self performed the concrete installation for the Tepper Quad building. The project included:

• 154 caissons
• 260,000 sf of cast-in-place walls
• 70,000 sf of slab on grade
• 510 columns
• 4 concrete cores
• 350,000 sf of supported slab
• 300,000 sf of voided slabs (“bubble deck”) at Levels 2-6

The building was constructed using a voided slab methodology that involved using approximately 220,000 hollow plastic balls sandwiched between the two reinforcing steel mats within the concrete slab.

By placing hollow plastic “bubbles” into cages that live between layers of steel rebar and then pouring concrete around the bubbles, the team reduced the amount of concrete in the building by roughly 25 percent. This method also reduced the amount of steel structure needed to support the floors, the weight of the floors, and the height that is typically associated with a steel and concrete structure, all while still providing the strength needed to support the building.