On a Saturday morning this spring, Jon Shores and about 70 members of the DPR team rose much earlier than the sun and headed to a leading enterprise software company’s campus in Pleasanton, California. They positioned 15 light towers around the site to illuminate what would become DPR’s largest ever self-performed concrete pour.
The 410,000-sq.-ft. commercial office space will become the company’s corporate headquarters when it is completed in 2019, and is a full cast-in-place concrete structure, unique in an area where most buildings are made of structural steel. The cast-in-place concrete structure will help foster a look and feel of structural, exposed concrete from a design perspective and reduce vibrations in the building for user comfort. To support the 3-foot thick concrete core walls that rise from the mat foundation all the way up seven stories to the roof, the team needed to build a thick mat foundation, as unique as the building it will hold up.
In 11 hours, DPR coordinated the pour of 4,800 cubic yards of concrete, reinforced with 1.2 million pounds of rebar. The foundation is notably 6 feet 6 inches thick in its center, and about 5 feet thick around the perimeter. Although the project is a large structure, the construction site itself is relatively small, bordered by a highway, a mall and a BART station.
The DPR team set up its own traffic control system to manage the nearby mall traffic and make sure the commercial hub and its shoppers were not affected by the 480 truckloads of concrete coming in and out of the site all day. The pour was serviced by four on-site concrete pumps and four concrete plants based in Pleasanton, Hayward, Oakland and Martinez. Because of the sheer volume of concrete needed for the foundation, the team was pouring as many as 500 cubic yards of concrete per hour. By the end of the day, the team had poured enough concrete to fill one and a half Olympic-size swimming pools, or 3.7 million 2-liter bottles of soda.
“We were able to pull this off because of the strength of the team we have on site, including our highly skilled craftspeople and their dedication to quality and safety,” said Shores. “Self-performing structural concrete allows us to set the tone and pace for the job and ultimately allows us to deliver a quality product to our customer.”
11 hours after that dark, early morning, the team celebrated the major milestone, as the successful completion of the mat foundation cleared the way to begin vertical construction on the core walls. Eventually 600 lineal feet of walls will rise above the mat, as the team continues to build great things–from the ground up.