Mat Pour for the Tallest Skyscraper in San Francisco

Currently, one of The Conco Companies’ large construction projects is the Salesforce Tower, which is slated to become San Francisco’s tallest building at 1070 feet high once it is finished in 2017.  For the project, we recently undertook the massive, continuous mat pour for the skyscraper that was over 18 hours from start to finish.    

The new 14-foot thick and nearly an acre in size concrete slab required approximately 12,000 cubic yards of concrete, which is enough to nearly fill four Olympic size swimming pools.  The pour started at midnight on November 7^th and utilized seven pumping trucks throughout the course of the job that had boom spans of 150 feet to 190 feet.   

The pumping trucks were constantly re-filled from 1,300 truckloads of concrete that came from several cement plants located around the Bay Area.  In order to create that much concrete, the cement plants needed 7,900,000 pounds of cement and 9,000 cubic yards of sand and gravel as well as 54,000 gallons of water.  In total the pour used almost 49 million pounds of concrete.

To get the ground prepared for the gigantic pour, crews had constructed a subterranean lattice that consisted of 5 million pounds of number 18 rebar that was 12 layers high.  Six inches separated each layer.  Number 18 rebar is the largest size available and each piece is 2.25” in diameter.  At 45-feet long, it required eight steel workers to lift a piece into place. 

Along with the 14-foot thick slab, engineers designed another step in an effort to provide the upmost earthquake protection for the building in the active seismic zone.  Part of the foundation also includes 42 piles that go all the way down into the bedrock, which is 300 feet below street level.   

The Conco Companies are a leading supplier of concrete services for the Western U.S.  We got our start in the Bay Area in 1959 by offering clients the best value on a wide range of concrete services and products.  Since that time, we have taken a leading role as one of the top concrete contractors in the region. We have four regional offices serving California, Nevada, Washington, Oregon and Colorado.

Source:

wired.com/2015/11/it-took-18-hours-to-pour-san-franciscos-biggest-ever-concrete-foundation/#slide-1