Hollywood hit men have taught us concrete galoshes will sink a body. University of Alabama at Birmingham engineering students are learning that concrete also can be used to keep a body afloat.
“Water has a specific gravity of one, and as long as the specific gravity of the concrete is less than one, it will float,” says Ethan Parker, a senior in the UAB School of Engineering. “It is a simple equation.”
Parker and his colleagues, members of the UAB chapter of American Society of Civil Engineers, are constructing a 20-foot concrete canoe to race against other universities on a slalom course during an ASCE competition in Tallahassee in March. The eight-foot model they tested recently quickly taught them navigating a concrete canoe is a metaphor for engineering itself.
“It’s a little difficult to get used to at first,” says Paisley Marotta, a senior majoring in Civil, Construction and Environmental Engineering at UAB. “You really have to find your center of balance, and any little thing you do is going to have an impact.”
This attention to detail captures the UAB crew’s focus. One wrong measurement in the mix and the entire project will sink. They compare the challenge to following a cooking recipe, but with ingredients many people can’t pronounce.
“We added Portland cement, VCAS, fly ash, xypex material, poraver, pelletized plastic and cenospheres,” says Parker. “And then we added strux BT-50 fibers, adva 575, V MAR 3, eclipse shrinkage crack reducer and of course water.”
It has been a few years since UAB entered the ASCE competition. Daniel Brown, the 2011 Alabama section ASCE Outstanding Student of the Year, spearheaded the return of the program this past year. He realized almost immediately they were up a creek without a paddle.
“Students from the past years had graduated, so we had a discontinuity with information and had to learn to build a concrete canoe from scratch,” says Brown, a UAB senior. “In a way it was good because everybody had to come to the table with new ideas, and we all learned a lot.”
The UAB team will spend more than 1,000 hours on this project. They will use more than 10 cubic feet of concrete — roughly a tower that is 10 feet tall and a foot thick and wide. The canoe will weigh 400 lbs. and carry an estimated crew weight of 650 lbs.
There is no time to test the official canoe before they compete. Are they worried?
“The density of water is about 62 pounds per cubic foot,” Brown says. “The density of our canoe will be somewhere around 58 to 60 pounds per cubic foot; based on the math it is going to float.”
So no, they are not worried.