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Tall Tales of a New Tower

Editor’s note:  This is the first in Kollaer’s four-part series about the Wilshire Grand Center.

The main stream media isn’t well known for covering construction stories, especially in depth, but Thomas Curwen and his colleagues at the LA Times did an outstanding report on the construction of what will be the tallest building west of the Mississippi in the Wilshire Grand Center construction. The five part series written by Curwen augmented by photos from his associates focuses the complexity and challenges during the planning and construction of a major project on a downtown constricted site that are usually not talked about openly in the press or outside of the owner, designers and construction teams.

The first article in the series documents the logistical nightmare that was the largest continuous concrete pour since the 1999 Venetian pour in Las Vegas. The mat under a 900 room hotel and 400,000 square foot office development is 18 feet thick and required 21,200 cubic yards of concrete poured around 7.1 million pounds of re-bar. There were 350 workers on the site and 227 concrete trucks bring the concrete to the 19 pumpers that got the concrete into the steel cage at the pour site.

The pour is seen through the eyes of Michael Marchesano, the veteran General Superintendent on the project for Turner Construction, general contractor for the project being developed by Korean Air. The graphics accompanying the story illustrate the pumping of the concrete from the trucks at ground level down to the “cage” where workers had to make sure that the slurry was spread evenly. They used long vibrators to make sure that there were no pockets left in the structure that might cause structural problems later. The testing company took over 1,000 concrete samples to test the “slump” and the strength of the concrete mix to ensure that there was a consistency in the concrete that was poured into the mat.

One of the most interesting points in the story is about the need to lay 90,000 feet of tubing to circulate 40,000 gallons of cold water over the pour to help dissipate the heat generated during the curing of the concrete after the pour. That system was necessary to ensure that the temperature did not exceed 160 degrees, the temperature at which the concrete would begin to lose its strength.

We will write more about this great series of stories in the LA Times and hope that you will want to follow along. As a “recovering architect” and former worker on a major construction projects, I was both intrigued and pleased to see the detail coverage of a project that will be the tallest in LA.

 


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