Upon completion in 2017, the new, 73-story Wilshire Grand project in downtown Los Angeles will be the tallest structure west of the Mississippi. The project kicked off in February 2014 with the largest continuous concrete pour as determined by Guinness World Records. After more than two years of work, the project has topped out its concrete and steel core at more than 800 feet.
To coordinate the fleet of pumps, including 16 Putzmeister units, required for the record-breaking, 21,200-cubic-yard mat pour, Turner Construction Co. the project’s general contractor, worked with Conco Construction Companies, one of the largest pumping and belt companies in the U.S. The pour included 227 ready mix trucks making more than 2,100 trips and pouring 82 million pounds of concrete during an 18.5-hour period.
Crew have pumped about 160,000 cubic yards of concrete vertically, including lightweight concrete and 8,000 psi mixes. A building of this height requires a pump that can maintain a balance between power and pressure to be able to deliver concrete floor after floor. The amount of friction that is generated during the pumping process as the concrete moves through the lines increases the higher the concrete is pumped. That friction has a significant impact on the plasticity of the concrete at the point of placement.
Once the crews started working on the vertical placement for the tower of the structure, they used a single placing boom on a tower climbing system. The typical vertical concrete floor was placed on a four-day cycle, which included jumping the climbing system.
“This strategic setup was the result of project upfront planning by Turner Construction and Conco. These measures maximized the rewards of using the Putzmeister pumping equipment,” says Michael Marchesano, Turner Construction’s general superintendent. “Every detail was measured, including redundancy pump station location, system sizing, and layout to enhance safety and avoid building sequence delays.”