Bay Adelaide Centre, a 52-story, 1.2 million-square-foot office complex in downtown Toronto, presented unique logistic and scheduling challenges. Contractors had only 25 months to complete the West Tower, including excavating and shoring down 60 feet into the parking deck, working back up to grade, and enclosing and substantially completing all 52 floors to be ready for tenants. The construction team met the demanding schedule while using materials and practices that would allow owners to submit the project for LEED Gold Canada certification.
Once the concrete mix was developed, contractors began incorporating existing foundation walls into the building's shoring design, cutting into the operating five-level parking garage and working from within. They used a hydraulic, self-jacking, corewall jumpform designed specifically for this project's multi-celled core (22 cells). Contractors jacked up one floor every three days. By starting at the P3 level, the team was already at level six on the structural concrete core wall when they completed the ground floor.
Construction of the building's core walls was the job's main challenge. The core walls required more than 22,000 yards of concrete—about one-third of the concrete on the entire job—and it had to meet unique requirements. The concrete had to achieve a compressive strength of 60 MPa (8702 psi) in 91 days, an 8 MPa (1160 psi) in 12 hours (non-air entrained mix), flow through vertical pumps more than 50 stories high, and qualify for LEED certification.
The team selected self-consolidating concrete, with Canada Building Materials' LISA maximizer. Formwork had to be almost watertight and be able to handle the concrete mix's added pressure, which was considerably higher than conventional concrete.