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UC Berkeley retrofits take "green" approach to concrete foundations
27 Dec 2000

By Kathleen Maclay, Media Relations

Berkeley - New foundations for the seismically retrofitted Wurster and Barker halls at the University of California, Berkeley are so "green" they'll save the pollutant-emitting equivalent of 1.5 million vehicle miles, or 60 car trips around the Earth.

The foundations incorporate high-volume fly ash concrete which requires far less fossil fuel to produce than conventional concrete. Fly ash is a byproduct of coal-burning power plants. The ash is created at high temperatures and becomes tiny, beady glass particles. Of the 60 million tons produced every year in this country, about 75 percent of fly ash is trucked off to landfills rather than converted into building material.

But enthusiastic design and construction teams working on UC Berkeley seismic projects say that the high-volume fly ash concrete mixture reduces environmental impacts and can save money while producing more durable concrete structures.

"Our main goal in these projects is to make sure that hose who study and work in these buildings will be safe in the event of a major earthquake. That we can do so in such an environmentally friendly way is a wonderful bonus," said UC Berkeley Chancellor Robert M. Berdahl.

The projects are signs of the progress of "green" building techniques.

"The sustainable design movement is really taking off," said Wurster Hall retrofit architect Scott Shell of EHDD Architects in San Francisco. "We're excited that an institution such as UC Berkeley is willing to be a pioneer in this effort."

Every ton of standard cement produced for concrete requires about 1.5 tons of raw materials. Project architects and engineers said standard cement also requires intense use of fossil fuel, so much so that its production worldwide accounts for about 8 percent of all carbon dioxide emissions from human sources. That is the equivalent of 330 million vehicle miles or 330 million pounds of carbon dioxide, the primary greenhouse gas causing global warming.

Using fly ash in nearly 1,800 cubic yards of concrete at Wurster Hall will spare some of the greenhouse gas emissions that would have resulted from producing conventional concrete. Wurster Hall is home to the College of Environmental Design. The project there represents pollutant savings in the use of cement the equivalent of 650,000 miles behind the wheel of a car, said Afshar Jalalian, a structural engineer with Rutherford & Chekene Consulting Engineers of Oakland.

About 2,500 cubic yards of 50 percent fly ash concrete will be also poured for foundations at Barker Hall as well, with comparable cost and environmental savings.

The two projects are part of the campus's on-going SAFER program, a multi-year $1 billion-effort to seismically strengthen more than a quarter of all buildings on the central campus to improve life safety in the event of a major earthquake.

Shell has been interested in sustainable design for about 10 years. He encouraged the university to request bids for fly ash concrete when planning the Wurster retrofit for both the performance and environmental benefits. The bid came in $13,000 less than standard concrete.

Although 50 percent fly ash concrete has been used for close to 15 years, it remains more popular in Canada than the U.S., where it remains less known. In California, cement with 15 percent fly ash is typical and the California Department of Transportation now requires 25 to 35 percent fly ash because of the improved performance benefits, Shell said.

The changeover to fly ash takes perseverance, he said, but even so, "It's not nearly as difficult as convincing 330 million people to stop driving."

Shell praised College of Environmental Design Dean Harrison Fraker and the college's faculty for being so supportive of sustainable design and informed about it. UC Berkeley also is home to the one of the world's leading experts in fly ash concrete, P.K. Mehta, a professor emeritus of civil engineering.

"When you're doing something new and different, the burden of proof is on you and you really need a team to make it work," Shell said.

EHDD used high percentages of fly ash in earlier projects, including for the tanks of the Monterey Bay and Long Beach aquariums, but Wurster Hall is its largest project so far using 50 percent fly ash, Shell said.

Crews poured 600 cubic yards of the fly ash mixture, or 400,000 pounds of fly ash plus cement, for the Wurster Hall foundations in November. Another approximately 700 cubic yards of the high-volume fly ash concrete will be poured on Friday (Dec. 29).

At Barker Hall on the northwest end of the campus, plans call for pouring the high-volume fly ash cement starting in April. Forell Elsesser Engineers of San Francisco has used the "green" concrete-mix in other projects, but this is its largest as well. The firm also plans to use fly ash for the foundations of a lab at UC San Francisco's Mission Bay campus.

"My hopes are that these efforts will set the standard for similar projects elsewhere," said Langston Trigg, UC Berkeley's associate vice chancellor for capital projects. "Successful dissemination of information about this approach and technology could have a significant effect on our environment."

Extensive tests on the UC Berkeley work are providing important data about fly ash performance that will encourage more architects, contractors and concrete makers to start using these concrete mixes, according to Shell.

With satisfactory bids for the material, crews then conducted a special trial batching and testing of the mixture as a quality control measure, said Jalalian, the structural engineer. There was additional testing involving trial casting on a small area to allow the contractor to become familiar with how the material sets after it is cast.

One drawback of fly ash is that it takes longer to gain strength and harden, which needs to be accounted for in the planning stages of any project, he said. Another sensitive consideration has been color, but Shell said that's a minor problem.