Special Report: Concrete Innovation

Concrete of the   Olympic Sculpture Park

Concrete shows its versatility, editors from across the  country report. In Seattle, one of the most difficult concrete projects from 2006 was at the Olympic Sculpture Park.

by Adrian MacDonald

When the Seattle Art Museum opens its new Olympic Sculpture Park on the downtown waterfront on Jan. 20, concrete contractors may have as much to appreciate as art buffs.

The nine-acre park, designed by New York architecture firm Weiss/Manfredi, is based around a 2,200 ft. Z-shaped gravel path covering an elevation change of 42 ft. from Western Avenue to the waterfront. Along the way, the path spans over four-lane Elliot Avenue and a Burlington Northern Santa Fe railroad line in a pair of bridge structures with little in common between them.

“That railroad bridge is as challenging a concrete structure as I’ve ever been involved in,” said Bill Badger, project manager for Sellen Construction of Seattle.  The railroad bridge architecture calls for sophisticated concrete formwork using Peri equipment. Peri is a German company that makes equipment for sophisticated concrete formwork, including one razor-sharp point of the “Z”  incorporated into the bridge structure. “You could split your head on it,” Badger said.

On either side of the bridge, trapezoidal abutments rise 33 ft., with several interior counterfort walls. The abutments often had to be poured in two lifts, Badger said.

The waterfront soils, meanwhile, required that the whole structure be supported on 124 steel pipe piles, each 16 in. diameter and reaching depths of 30 to 40 ft.

The abutments are within 25 ft. of the tracks on either side, so Sellen had to hire BNSF flagging personnel and sometimes stop construction as trains passed.

The railroad bridge is also skewed at such an extreme angle over the tracks that project engineers at Magnusson Klemencic Associates of Seattle had trouble fitting the required steel girders under the 124 to 142 ft. span to meet train clearance.

“The architecture and engineering on this project is woven together more intimately than I’ve ever seen,” Gangnes said.

Perhaps the architects’ most innovative use of concrete was decorative rather than structural. At both the roadway and the railway, the mechanically stabilized earth walls are faced with eight in. thick custom precast concrete panels in an overlapping pattern, a radical departure from typical earthwall facing. Each panel is ten to eleven ft. wide and as high as 36 ft.

In parts of the Z-shaped path that require safety barriers for pedestrians, such as around the bridges, the concrete panels extend as much as 8 ft. above finish grade to double as handrails.

“The architects kind of frowned when we suggested mechanically stabilized earth because they didn’t want this thing that looked like a highway embankment,” Gangnes said. He added that Weiss/Manfredi warmed to the idea when the firm learned how much flexibility the precast panels allow a designer.

“These retaining walls are woven into the design,” said Michael Manfredi, principal with Weiss/Manfredi. The overlapping panels are moveable with earth movement like fish scales, “so this ho-hum wall actually looks good,” Manfredi added.

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Solidifying the Future

In the wake of record construction activity, construction teams have turned to concrete innovations to get the job done.

by Bruce Buckley

A construction boom coupled with designers and contractors looking for faster and better ways to deliver projects for owners have created an ideal environment where concrete innovation has thrived in recent years. Although the acceptance of new technology in concrete has traditionally been a slow and methodical process in the United States, market forces have converged to drive the use of more emerging mixes and applications.

Increased construction activity nationwide has spurred greater use of concrete. In 2006, consumption of Portland cement, a main ingredient in concrete, is expected to reach a record 124 million metrics tons – reflecting 2.3 percent growth over 2005, according to the Portland Cement Association. Even as construction activity is predicted to cool in 2007, the market should record another 1.3 percent gain in 2007.

Rising costs over the past five years of other building materials, such as steel, have helped contribute to the popularity of concrete. Additionally, durability and speed of delivery have been factors. With owners looking to have projects completed faster, use of precast concrete has risen dramatically. In 2005, use of precast increased by 17.5 percent compared to 2004.

Ty Gable, president of the National Precast Concrete Association, said precast has reached greater popularity as owners request more fast-tracked projects and contractors struggle with labor shortages.

“It’s more and more of a challenge on the jobsite to get the skilled labor necessary, so architects and designers are turning to precast,” he said.

In many cases, they also want them to last longer. Durability has become an increasingly important aspect of the developer’s equation on infrastructure projects, especially as more private entities have begun to invest in roads and bridges, said Steve Kosmatka, vice president of research and development at the Portland Cement Association.

“Public-private partnerships create an opportunity for people to use innovations, as opposed to the standard designs that have been in the books for 30 years,” he said. “PPPs are willing to take risks especially if they see it reduces maintenance. Banks that look at these projects want technology that will allow contractors to put down a bridge or highway that won’t have to be touched for years.”

The trend is promoting greater interest in use of ultra-high performance concrete, also known as reactive powder concrete, which is nearly five times stronger than conventional concrete. Although it has been used abroad, researchers are testing it here in the U.S., including a new bridge built in Iowa that is the first in the country to use the material.

Michigan’s Department of Transpor-tation and University of Michigan scientists are testing the use of a new fiber-reinforced “bendable” concrete, also referred to as engineered cement composites concrete. Because it can bend, ECC reportedly is less likely to crack and fail. It’s also nearly 40 percent lighter than conventional concretes.

“Traditionally, DOTs have been very conservative – they don’t want to take risks,” Kosmatka said. “To see them take an interest in doing these things on their own is very promising.”

Despite early progress, the same barriers to acceptance remain – without broadly recognized specifications and testing methods, limited numbers of engineers will take risks on new materials.

“You can’t go to the building codes and find out how to use these materials,” Kosmatka said. “The average engineer at the average firm wouldn’t know how to use them.”

Despite this, the demands of developers often prevail. Pervious concrete has gained tremendous interest among developers as an option for storm water management. Water passes through pervious concrete where it is filtered by the concrete matrix. Using pervious concrete on parking lots could allow developers to avoid dedicating a portion of their site to retention ponds, thereby saving them money on land costs.

Dan Huffman, director of natural resources at the National Ready Mixed Concrete Association, said he hopes that pressure from owners will prompt the industry to embrace pervious concrete.

“Agencies and owners of sizeable companies, like WalMart, are slobbering over this technology,” he said. “We just need to get our act together in terms of having concrete producers who can make the material and contractors that can put it down.”

The potential of pervious concrete is one of many ways that concrete is riding the trend toward more environmentally-friendly developments. Use of pervious concrete, for example, can be used to gain points toward LEED certification. In some cases, designers are using recycled materials as aggregate in concrete to gain LEED points.

Researchers in Italy are pushing the envelope even further. Italian producer, Italcementi, have produced a so-called “smog-eating concrete.” The material contains titanium dioxide, which, when triggered by sunlight, absorbs pollution and releases it as non-toxic gas. As a result, the concrete also stays clean.

While cutting-edge advances could have an impact in the coming decades, many are looking for yesterday’s innovations to become the norm. Lionel Lemay, vice president of technical resources at the National Ready Mixed Concrete Association, said he sees self-consolidating concrete as having the greatest room for expansion in the industry. The labor-saving qualities represent a main reason he expects it to gain greater acceptance in the coming years.

“Anything that reduces labor is a positive these days,” he said. “If it saves having to put someone out in the field to vibrate the concrete, that’s a plus.”

The growth in SCC has trended along with increased use of precast concrete. The NRMCA estimates that 40 percent of precasters use SCC. Meanwhile, researchers continue to experiment with new applications for SCC. A project underway at Iowa State University is tackling one of the more challenging potential uses of SCC – paving.

“I believe eventually all concrete could meet the self-consolidating definition,” Lemay said. “At some point there will never be a need to vibrate concrete anymore.”

Career in Concrete

By Adrian MacDonald

Dave Frentress is a man passionate about concrete.

Not a passion, perhaps, that the rest of the world would immediately understand. But as Frentress gets rolling on the subject, the Glacier Northwest marketing director’s enthusiasm for the subject is surprisingly infectious.

“People take concrete for granted,” Frentress says. “You can do so many things with it—vertical, horizontal, colored, polished, stamped with wood shapes. You can make it pervious or impervious. In the past 30 years there’ve been a lot of innovations.”

One of Frentress’s favorite things about concrete, is its potential as a “green” building material of the future. “It’s important for the concrete industry to step up our way of thinking,” he says. “I push to get people to realize the environmental benefits of concrete. I make presentations to architects, engineers, owners, on why it’s a smart choice for life cycle costs.”

“Increasingly green is the driving force in the marketplace,” says Dan Huffman, Managing Director of National Resources for the National Ready Mixed Concrete Association. Frentress was the association’s “Promoter of the Year” in 2005. “Dave is definitely on the cutting edge of the sustainability movement,” Huffman adds. “He’s an extremely good presenter, and he’s a great supporter of the concrete industry. ”

Among the novel environmental applications Frentress says customers are surprised to hear about is “pervious concrete,” a mix that allows water to percolate through it. “Your parking lot can be a water transport system,” Frentress says. Pervious concrete can take the place of stormwater drains, provide water filtration, and feed directly to groundwater. It also contributes to a building’s LEED rating.

Going the other direction, concrete can also be impervious. In that form, Frentress says, it makes an inexpensive alternative to the waterproof membrane on a green roof. “I do presentations to groups like the Green Roof Show,” Frentress says. “How many concrete people do you think are there? Right: one. Me.” But for a green roof, he offers, impervious concrete can provide a $3 per square foot solution where a membrane system would cost $15 per square foot.

“Green building is the future, and concrete has a lot to offer those people, environmental-wise,” Frentress says. Another application he sees starting to take hold is walls built with insulated concrete forms instead of wood. According to Frentress, concrete conserves more energy, is 3 times quieter, and is not subject to rot over time. Glacier is currently supplying a 5-story building in Portland, the Lane Building, with insulated concrete forms. “You can put on an external application, so you don’t see the concrete from the outside. It’s 99.99% efficient. And with concrete nothing can go wrong. It has a good fire rating, and stands up in earthquakes and tornados.”

Frentress’s career in concrete has spanned for 30 years, starting when he was a road worker in North Dakota paying his way through college. “My first job was Interstate 9, just straight and flat,” he says. “Our biggest accomplishment was 2.2 miles, 10 inches thick, in one day. It set the world’s concrete paving record at the time.”

For his master’s thesis at Wilfred Laurier University in Ontario, Frentress says he drove every back road in northern Ontario, making pavement ratings for a study on rural transportation access. After graduation he would go on to spend over a decade on the road, from driving a mixer truck (“very bumpy,” he says) to traveling as a sales rep for concrete companies like MTM Mixers and Schwing America.

“The interstate highway system was never designed for as much truck traffic as it has now,” Frentress adds. “We have concrete roads that have held together for 60 years. If taxpayers understood the benefits of concrete in terms of life cycle, they would demand it over asphalt.” On a road like Interstate 5, he says, trucks on concrete get 8 percent better fuel economy than asphalt, because the rigid surface creates less rolling resistance.