Looks pretty sleek, but can a concrete canoe really float? The answer is yes – but the trick is finding a concrete that is less dense than water. Known as the ‘Pre-Castaway,’ this lightweight wonder was created by students at the University of British Columbia. Over the course of an academic year, the team of volunteers gained experience with design, materials technology, lab work and in addition, got some very practical construction experience.
To create their concrete canoe, the team imported a material called Poraver from Germany. This is an expanded glass-ceramic product that provides buoyancy, with specific gravities ranging from 0.4 to 0.7, depending on gradation. After working out mix designs for specific gravities, they used a trial mix design process whereby they batch and test different mixes, varying the parameters to find the ultimately concrete composition. They used four to eight test cylinders that were 3” in diameter and 6” long for each trial batch. The test cylinders were then moist cured for 28 days.
Each year, the team competes in the ASCE (American Society of Civil Engineers) National Concrete Canoe Competition. Last year they placed fourth and are aiming for a top three finish next year in Idaho. You can find out more the project and follow their progress here.