Concrete is heavy, and 5% of the world’s CO2 is created during the manufacture of the cement that goes into it. Then there is the aggregate that is dug out and the trucks that have to carry it. Not only that, but most of the concrete that is in a slab isn’t even needed; it is just a spacer between the bottom, where the reinforcing steel is in tension, and the top, where the concrete is in compression.
BubbleDeck is a really clever solution to this problem: it fills the slab with plastic balls that are held in place in prefabricated assemblies of reinforcing. It has been used a few times in Canada, and Archdaily shows the first above-grade installation of BubbleDeck in the United States, at Harvey Mudd College.
BubbleDeck is a biaxial technology that increases span lengths and makes floors thinner by reducing the weight while maintaining the performance of reinforced concrete slabs. The concept is based on the fact that the area between columns of a solid slab has limited structural effect beyond adding weight. Replacing this area with a grid of “voids” sandwiched between layers of reinforcing welded wire steel and an internal lattice girder yields a slab typically 35% lighter that performs like solid reinforced concrete. Once the steel lattice/void “sandwich” is concreted, it is then precast into panels of various sizes and craned into position on shoring. Once concrete is poured over the balls in the panels, the BubbleDeck system effectively becomes, and behaves like, a monolithic two-way slab that distributes force uniformly and continuously.
Bubbledeck Canada claims that it produces floors 20% faster with less formwork and beams, reduces construction costs by 10% and agrees with the 35% reduction in concrete use. “Off-site manufacturing, fewer vehicle movements and crane lifts and simple installation all combine to minimise operating as well as health & safety risks.”
Replacing concrete with….air. I wonder why this isn’t used everywhere.