On the journey to the American Society of Civil Engineers’ (ASCE) 2011 National Concrete Canoe Competition, some students towed their canoes more than 2000 miles cross-country. Some worked through holiday breaks to keep their projects on schedule. And some practiced paddling through frigid mountain rivers for hours on end—all for the chance to compete at the University of Evansville in Evansville, Ind., June 16–18.

The annual contest challenges students to put their knowledge and creativity to practical use, and tests their project management skills. Each year, the teams spend hundreds of hours working on their canoes. If they win a regional competition, they qualify for the national event.

Teams are judged equally in four parts: a design paper, oral presentation, final product, and the canoe’s performance in five different races. In June, the top three teams took home a combined $9000 in scholarships for their respective civil engineering programs.

“This year’s requirements limited the amounts of certain kinds of recycled materials, and forced the students to think beyond glass spheres,” says Mark L. Valenzuela, PhD, PE, associate professor for the Department of Mechanical and Civil Engineering at University of Evansville and a home team advisor. All concrete mixtures were required to contain at least two sustainable aggregate sources, each making up at least 25% of the total amount of aggregate; only one could be glass microspheres.

University of Evansville’s home team experimented by adding corn husks and corncobs—locally abundant materials—to the concrete for its canoe “Crux Scrutum.” When the corn’s sugar content created an unexpected retarding effect, the students settled on ceramic spheres, chopped nylon, and chopped plastic bottle caps.

This year, ASCE’s Committee on National Concrete Canoe Competition (CNCCC) permitted students to use “nondeleteriously reactive aggregates,” siliceous sands with some pozzolonic qualities. Water-cement ratio and air content requirements were removed, although the teams still had to correctly calculate air content.

Paddling to victory

Engineering students from 24 universities met for the aquatic showdown in Evansville. They spent two intense days of setting up, displaying their canoes, and making academic presentations. Then the teams waited a few more hours, for morning thunderstorms to pass, before they could finally race at John James Audubon State Park in Henderson, Ky.

For the second year in a row, California Polytechnic State University, San Luis Obispo, won first place—but not with the same team. In fact, without a single returning team member the new group faced a steep learning curve. “We had to teach ourselves the techniques and methods that had been used before, and put in a lot of extra hours for mistakes we made along the way,” says captain and project manager Chad Inlow.

Their efforts produced a 208-pound canoe, “Cetacea,” named for a biological order of marine mammals. Its thin hull was reinforced with aircraft cable encased in a Teflon sheath.

They used latex to add tensile strength to the hull, which also helped reduce density by frothing and adding air content when mixed. Unfortunately, the air content took the form of large, unstable bubbles, so the team added an air-entraining admixture as a stabilizing agent. To meet the competition’s minimum density requirement - 55 pounds per cubic foot - without reducing tensile strength or stability, they also added an air-detraining admixture.

The team found an innovative way to meet its sustainable aggregate requirement. ”We brainstormed for weeks trying to come up with a new aggregate, but nothing seemed to match the requirements—strong, relatively lightweight, sustainable, light colored. For those two weeks, everything I looked at was a potential aggregate,” remembers Inlow. After he was inspired during a trip to the restroom, the team decided to use 600 pounds of ground porcelain from crushed toilets.

But, according to Inlow, Cetacea’s aesthetics were its strongest asset. The winning canoe features an inlaid rail, plus one curved and one square bulkhead. It is decorated with more than 30 brightly colored graphics, including cast-in-place and precast tiles. 3D elements?an intricate coral piece and a turtle—grace each bulkhead.

Stiff competition

University of Wisconsin-Madison placed second with “Element”—a 191-pound canoe made of integrally colored concrete, with fiberglass mesh as reinforcement. “Placing second without any staining on the boat was incredibly significant,” says co-chair Stephen Ward, a third-year competitor. “Our team likes the look of integrally colored concrete, with inlays and overlays. We used a gradient finishing technique on the interior inlays that kept our aesthetics competitive.”

The team has used 100% recycled aggregates in its canoes since 2006. This year, their materials included palletized slag and recycled cellulose magazine fibers. They also chose an environmentally friendly plaster and burlap mold to cast the canoe, rather than fiberglass or Styrofoam.

According to Ward, the team’s most innovative choice of materials was using linoleum flooring as an inlay placeholder—a less costly and easier alternative to vinyl stencils and mounting tape. Their biggest hurdle: scheduling the finishing process. “We had a much more intricate design than previous years, with more colors,” he explains. “Planning when to place and finish each color was very challenging.”

Université Laval of Quebec, Canada, won third place with “Voltage.” Its 103-pound canoe—45 pounds lighter than the next lightest competitor—raised the competition’s bar for thin, lightweight design. The team cast its 1/4-inch shotcrete hull monolithically, incorporating ribs and rails, and used carbon fiber mesh reinforcement.

David K. Lewis, PE, a Transportation Division bridge engineer for the County of Santa Barbara, Calif., served as a judge for the second year in a row and has become an advocate for the program. “The canoe competition has really given me great confidence in up-and-coming engineers,” he says.

The competition continues to grow, with two new competitors joining the pack in 2011: Utah State University and Minnesota State University, Mankato. University of Nevada, Reno, will host the competition in 2012, its 25th anniversary year.

The ASCE Committee on Student Services encourages the concrete industry to get involved in the competition—a unique opportunity to meet and support some of the best and brightest young engineers. To volunteer as a judge for a competition, email student@asce.org.

Videos: University of Wisconsin - Madison Concrete Canoe Animations
University of Wisconsin - Madison's team created a digital animation to show how its canoe "Element" was built, layer by layer.

Mold construction process: A prototype canoe was made by attaching plywood cross sections to a strongback and covering it with marine-grade plywood. Plaster-soaked burlap sheets covered the prototype to form the mold. Last, the mold was flipped and the prototype was removed.

Construction process: Element is made of three layers of concrete (blue, 'uncolored', and black), two layers of fiberglass mesh, and six steel prestress cables running the length of the canoe. The animation shows the order of each layer/reinforcement piece.