A group of researchers at the Masssachusetts Institute of Technology (MIT) are testing new ways to use bamboo in engineering building materials in a manner akin to wood composites such as plywood, orientated strand board (OBS) and glue-laminated timbers.
Traditionally, when bamboo is used in construction, either the whole stalk is utilised in a lattice fashion (to make scaffolding, for example) or strips of the stalk are woven together to create screens or mats.
But the MIT researchers are applying bamboo in a different way. The idea is that a stalk, or culm, can be sliced into smaller pieces, which can then be bonded together to form sturdy blocks. A structural product of this sort could be used to construct more resilient buildings – particularly in places such as China, India and Brazil, where the fast-growing grass is abundant.
"There are several interesting things about bamboo as a material," says Lorna Gibson, the Matoula S. Salapatas Professor of Materials Science and Engineering at MIT. "The first is that it grows very fast and if you take an acre of land, people have shown that you can grow more mass of bamboo than you can of wood. It is a renewable resource. Another interesting thing is that it actually has very good mechanical properties."
If you compare the properties of bamboo with the typical woods used in structural engineering, it has very comparable stiffness and strength, Gibson explains.
This was revealed through mechanical testing by the researchers who looked at sections of bamboo from the inside out, noting each sample’s radial and longitudinal position along a culm, then gauged the stiffness and strength of the samples by performing bending and compression tests. In particular, they performed nanoindentation, which uses a tiny mechanical tip to push down on a sample, in order to gain an understanding of bamboo’s material properties at a finer scale.
"We're hoping in the end that this material will be more widely adopted," Gibson says. "Especially in developing countries that have a lot of bamboo resources. And to show that you can use it in construction in a way that is analogous to wood products."