Concrete floats, and pigs aren't flying

Cal Poly’s civil engineering students may not be able to make water into wine, but they can make concrete float. They can also mold it into a mean, lean racing machine, or in this case, a canoe. They did just that at this year’s American Society of Civil Engineers’ National Concrete Canoe Competition, placing fourth out of 22 student teams.

The competition – which was held in Montreal, Canada June 19 through June 21 – required students to design, build and then compete in endurance and sprint races with their concrete canoes.

“The whole competition is four parts,” said Jason Marshall, project manager of Cal Poly’s concrete canoe team. “The aesthetics, the paper explaining our mix design and our structure analysis, our (oral) presentation . and then races.”

The team won fourth place for the aesthetics, the paper and the races, and eighth place for the presentation.

Cal Poly is no stranger to success with last year’s team placing fifth and, two years before, second place. Cal Poly had to beat out 16 teams from schools such as UCLA, USC, UC Irvine, Cal State Fullerton, Long Beach State and students from Arizona, Hawaii and Nevada in order to win the regionals and advance to the national finals in Montreal.

Although it may seem impossible to some to make a buoyant canoe out of the concrete, Marshall said it isn’t really such a rarity.

“It’s not really a huge deal to have concrete floating,” said Marshall, who is a civil engineering senior. “In reality, concrete actually floats in water. It’ll float no matter what.”

Even so, Jason Kump, a civil engineering senior and mix designer for the canoe, said the concrete used in the canoe had to be unique in order to make a suitable watercraft.

“It’s called structural lightweight concrete and the basic reason it floats is because instead of using rock aggregate, like you see in normal sidewalks, we use a lightweight aggregate made of hollow glass,” Kump said. “We also use different types of cement that are lighter than standard sidewalk cement (and) make the concrete more porous so it’s more like a sponge and it will float that way as well.”

Kump added that building the canoe was similar to building a swimming pool.

“We (fit) a mold out of foam to the geometry of the canoe that we want,” Kump said. “In each layer, we use three one-eighth inch layers of hand-placed concretes and there’s (mesh) reinforcement in between each layer.”

The team decided to give the canoe a California theme focusing on Big Sur.

“On the inside of the canoe we inlaid concrete tiles representing different aspects of California,” Marshall said. “We had the beaches of San Diego, the golf courses of Southern California, Disneyland, a (Cal Poly) Mustang, the Golden Gate Bridge and a redwood forest.”

The students dyed and stained 144 of the tiles on the inside of the canoe and added a motif of Big Sur’s Bixby Bridge on the outside.

“The thing I learned the most was coming up with creative ways to get around problems,” Marshall said of the project.

“Being in this competition is not like reading a textbook where you’ve got to look up some formula to figure out how to solve your problem. You have to.go to Home Depot to pick up whatever supplies you can to figure it out, or use whatever tool you have in the shop. It’s really hands-on.”

With the team starting the canoe last fall, it took about 65 students, including seven team captains, roughly 3,800 hours to create this year’s canoe, which, according to construction captain James Elsberry, was a huge improvement in mix design over previous canoes.

“This year, we built a relatively light canoe; 174 pounds,” said Elsberry, who paddled in the competitions. “So that was a big improvement over years past where we’ve had 230-to 250-pound canoes.”

Even with this year’s lightweight model, the students had to take caution when taking the 6,400-mile trip to Montreal and back. The team members had to fit the canoe, its display case, a representative cross section of the canoe, a display board and their bags in their rented trailer.

“It took coordination and just a lot of packing effort to get everything in there,” Elsberry said. “With our 25-foot trailer we always end up wishing we had a little more room.”

Once there, Elsberry and the other paddlers were able to put to use the paddling skills they had been practicing for months.

“Honestly, it’s not all that different from paddling a regular canoe,” Elsberry said. “I mean, yes, it’s heavier, but you just have to compensate for that and paddle harder.”

Elsberry said that when competing in the sprint races, the turning technique was key.

“A lot of the top teams are neck-in- neck in the straightaway but it’s the turn that really sets them apart,” Elsberry said.

Although team members were pleased with their accomplishments in the competition, they were proudest of how well they worked with one another.

“What I’ve always liked about our teams for the past two years is everyone has always listened to everyone’s opinions,” Kump said.

“We don’t just brush each other off and say, ‘That’s a stupid idea.’ I hope I can have as many teams in the future that can do that but I don’t think I will.”