For two years I was part of the concrete canoe team of study association KOers. Almost every year the goals are to make fun with a few traditional Canadian canoes and to win the innovation award with a special designed or manufactured canoe. In 2015 we won the innovation award with a Vacuumatic Concrete Canoe.
The Vacuumatic Concrete Canoe was shaped and cured when it was subjected to a vacuum pressure. The concrete was poured on a foil that was placed on a flat surface. A breather material was placed on top of the wet concrete to obtain a more uniform vacuum pressure inside the sealed bag. This bag was created by placing a second layer of foil on top of the breather material. The bag was closed with special sealant tape. After applying a vacuum pressure the sealed bag was hung in an elevated wooden frame. During curing the vacuum pressure was still applied to obtain a more uniform wall thickness. The canoe was ‘demolded’ by removing the vacuum-bagging equipment. The process resulted in a canoe with characteristic ‘wavy’ edges as a result of the way the vacuum-bagged concrete mortar has been ‘hung’ from its supporting framework. Advantage of this method is that more free-formed shapes can be created without the need of expensive formwork. In addition, the concrete is cured in a sealed bag which has a positive influence on the mechanical properties.
The work I did was for most of the time in the lab. I was always trying to figure out how new ideas would work out. I prepared and tested several concrete specimens, and carried out various experiments to form and built the Vacuumatic Concrete Canoe. In 2016 we also tried to 3D print an concrete canoe, unfortunately we couldn’t finish this canoe on time. I liked to compete in the concrete canoe competition because of the hard deadline. In 2016 this deadline was not in our favor, however, in 2015 it resulted in beautiful characteristic shaped canoe because of the rigorous decisions we had to make.