Concrete examples of engineering

Concrete examples of engineering

UI hosting engineering event this week which pits custom-made craft from all over the world

URBANA — The word "concrete" is not often followed by "canoe."

It seems rather counterintuitive: Concrete shouldn't float, right?

Tell that to the engineers.

It's all about water displacement, not just weight, and years ago, a University of Illinois engineering professor decided a concrete canoe would be a good project to teach students that principle, among others.

Which brings us to the 2013 National Concrete Canoe Competition being hosted by the UI this week.

Nearly two dozen custom-made canoes from across the country will be on display Thursday on the College of Engineering's Bardeen Quad, just north of Green Street. After presentations to judges on Friday, the three-day event will culminate with concrete canoe races Saturday at Homer Lake.

Though the modern concrete canoe was born at the UI decades ago, this is the first time the campus will officially host the national competition (the lack of a natural body of water may have something to do with it).

Back in 1970, civil engineering Professor Clyde Kesler started concrete canoeing as a class project to teach students about using concrete as a building material, according to a history put together by Armen Amirkhanian, graduate student adviser to the current UI team.

The students eventually completed a 370-pound behemoth that "vaguely resembled a canoe," Amirkhanian said. Students at Purdue University heard about the project and challenged the UI to a race, which took place in May 1971 at Kickapoo State Park in Oakwood. The Illinois students bested the Boilermakers in three out of five races — but only because Purdue's canoe was swamped. The UI team declared itself 1971 world champs.

Gradually more universities became involved, and the American Society of Civil Engineers organized the first National Concrete Canoe Competition in 1988. The contest has grown internationally, today reaching countries such as Canada, Germany, Japan, South Africa and the United Arab Emirates.

This year's entry from the UI team — known as the Boneyard Creek Yacht Club — is a sleek, fire-engine red number named Vincere (meaning "to conquer" or "to win" in Latin).

The canoes use a higher-tech version of concrete, typically made of rock, sand, cement and water. Instead of crushed granite or limestone from a quarry, the canoe-builders use synthetic aggregates, such as perlite, vermiculite or even Styrofoam.

The UI team's "rock" this year is 92 percent microscopic hollow glass bubbles, normally used as a thickening agent in epoxies or automotive paint, and 8 percent recycled concrete from an old runway at Chicago's O'Hare International Airport.

"The rules change every year. This year, you can use any aggregate you like," said Amirkhanian, who has been working with concrete canoes since he was a child tagging along after his father, who was the concrete canoe faculty adviser at Clemson University.

The glass bubbles are tiny but mighty. They're so small and lightweight that a bag full of them would flow like water, he said. A cubic foot of the bubbles weighs just 9 pounds, as opposed to 62 pounds for water. But they can support 10,000 pounds per square inch. The glass bubbles make automotive paint and boat hulls smoother, as the finish is easy to sand and polish, he said.

"If you touch it, you would not believe you're touching concrete," he said.

The project takes some imagination, said UI junior Hong Kim, team co-captain along with Min Yin.

"No one really makes a canoe out of concrete. There isn't really a rule book. It's hard to find the right mix," he said.

The canoe weighs 170 to 180 pounds, fairly typical for this year's entries, he said. The lightest canoe in the history of the competition was 60 pounds, and some exceeded 400 pounds.

"It just needs to be able to hold the paddlers," Amirkhanian said.

Which it usually does — though not always. It's rare at nationals to see a canoe completely sink, but "sometimes during races, the team will actually finish the race under water," he said.

Amirkhanian knows this firsthand. Back in 2008, as an undergraduate, he competed for Clemson at the national competition in Montreal, and his team finished under water.

"We were sitting in the canoe on our knees, and the water was up to our waists," he said. "It looked like we were floating on the water paddling. Our heads weren't under water, but it was getting pretty cold."

The team finished ninth. There's actually a picture of his team at the start of the race in the Wikipedia entry for "concrete canoe." (He's in the second boat from the front.)

Each team at this week's national competition qualified during regional competitions earlier this spring except the UI, which failed to place in regionals but is allowed to compete as host. The UI's best finish ever was fourth place. Amirkhanian is hoping to crack the top 10 this week, noting that the team has improved significantly in the last four years.

On Thursday, from 7 to 11 a.m., each team will weigh its canoe, then purposely swamp it in a tank to see if it will float to the surface. If it doesn't, "that's a huge penalty," he said.

The boats will then be displayed after lunch, with a cross-section showing all the different layers of construction for judges to examine. On Friday, competitors will give presentations about how their canoes were built and answer questions from judges. The races are scheduled from 8 to noon and 1 to 3:30 p.m. Saturday at Homer Lake.

For more information about the competition, go to: http://www.asce.org/concretecanoe or cee.illinois.edu/concretecanoe2013.

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