Sustainable Concrete Canoe
CHRISTOPHER BLELLOCH CARLY SCHAEFFER ANTHONY SALGUERO
Yes, it floats.
Every year, the Cal Concrete Canoe competition team participates in the ASCE-sponsored competition to design, construct and race a canoe made out of concrete. While the design and construction are an important learning tool for students on our team, we feel that ordinary concrete canoe techniques and materials place a considerable environmental strain on both the campus and the environment as a whole. By replacing our portland-cement based concrete with geopolymer concrete, and constructing a re-usable wooden mold to take the place a of polystyrene foam mold, we hope to significantly reduce the carbon footprint of our concrete canoe. The wooden mold was constructed using wooden strips, wood glue, and a brad nailer.
A layer of plaster was applied to fill in cracks.
Reusable Wooden Mold
In the past, our team and the vast majority of competition teams throughout the country have utilized either a CNC-milled foam mold or a custom fiberglass mold to cast the canoe. It is practically impossible to reuse or recycle either of these molds following the completion of the project each year. This year, we constructed a reusable wooden mold system using FSC-certified wood to ensure our materials are sourced from sustainable forests.
Geopolymer concrete on casting day.
Digital rendering of wooden mold construction process.
Reinforcement was fastened to the canoe by precast concrete spacers.
Geopolymer Concrete
Traditionally, these canoes are made primarily of OPC (ordinary portland cement), the most widely used concrete throughout the world. However, OPC is known to have a considerable carbon footprint, and the construction industry’s reliance on this technology contributes to roughly 8% of the world’s CO2 emissions. Geopolymer concrete is an emerging alternative that offers up to an 80% reduction in carbon footprint.
Summary
A detailed Life-Cycle-Analysis (LCA) of the materials and construction process confirmed that the implementation of this construction scheme significantly reduced product waste and the use of the geopolymer mix reduced the canoe’s global warming potential by 35% compared to the portland cement based product used in previous years. Likewise, the team continued its use of 100% recycled aggregate making BEAREA 51 Concrete Canoe’s most sustainable canoe to date!
Sustainability Game-Changers
The canoe was cast in 90 minutes to 5/8th in thickness.
Acknowledgements
This project was made possible by a $2,000 grant from The Green Initiative Fund (TGIF). Special thanks to Cruz Carlos, Concrete Lab Manager and the Berkeley Department of Civil and Environmental Engineering
Bearea 51 at the 2015 ASCE Mid-Pacific Conference. Paddler Nicole Yee before racing the canoe at Lake Natoma.