Engineered Bamboo: The Green Evolution 3

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Friday, September 19th, 2014
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Bamboo is an appealing green building option but there are limitations to the product. MIT researchers are looking for ways to engineer the grass to create a more structurally sound material similar to plywood.

In collaboration with architects and wood processors from England and Canada, the research team has been investigating the idea of slicing the stalk, or culm, into smaller pieces and then bonding them like wood composites to form sturdy blocks.

Although the effect created by using traditional bamboo can be spectacular, the material is susceptible to insect damage and its hollow, cylindrical form limits both the shape and durability of buildings that make use of it.

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There are already a number of similar bamboo products in development but the MIT project intends to gain a better understanding of their behaviour so that they can be more effectively used structurally.

Very few species of bamboo have been classified, and the lack of knowledge of the material’s microstructure has impaired efforts to design efficient, optimal structural products.

“MIT’s work is very timely and has great potential to support development of the sector,” said Oliver Frith, acting director of programme for the International Network for Bamboo and Rattan.

“While bamboo has similarities to wood, the material also has very distinct properties. Although current approaches to developing structural engineered bamboo have tended to focus on mimicking engineered wood products, the future will probably lie in innovating new approaches that can better enhance the natural advantages of this unique material.”

In-depth analysis of the microstructure of bamboo has uncovered its potential for use in composite materials with stronger and denser properties than softwoods such as pine, fir and spruce. Bamboo also grows significantly faster than commonly-used trees such as pine, reaching heights of 20 metres in a matter of months.

Using electron microscopy, the MIT researchers obtained images of the bamboo microstructure and created complete, microscale cross-sections of the entire culm wall at different heights along the stalk. They gauged the stiffness and strength of the samples by performing bending and compression tests. The outer walls, they found, are particularly dense.

Using this data, a model has been developed which predicts the strength of any given section of bamboo and bamboo type which may help wood processors determine how to assemble a particular bamboo product.

“If you wanted a bamboo beam that bends, maybe you’d want to put the denser material at the top and bottom and the less dense bits toward the middle, as the stresses in the beam are larger at the top and bottom and smaller in the middle,” explained Lorna Gibson, the Matoula S. Salapatas Professor of Materials Science and Engineering at MIT.

“We’re looking at how we might optimize the selection of bamboo materials in the structure that you make.”

With bamboo growing extensively in regions where there are rapidly developing economies, Gibson said it is a good alternative material to concrete and steel but admits that the potential for the time being remains with low-rise structures and houses rather than complex skyscrapers.

Hong Kong does often use bamboo as scaffolding in skyscraper construction. The practice, however, has been banned in China.

The Big Tree Factory in Ubud, Bali is currently said to be the world’s largest commercial structure made from bamboo, sprawling across 23,500 square feet.

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3
  1. John Doyle

    Bamboo has an assured future in the world of the future, which is going to be a world of energy poverty and low tech capacity.
    Bamboo is a ideal material almost without peer. It can't miss!

  2. Conrad Maramag

    maybe bamboo tiny strips canbe glued in layers, as middle layer of plwood for use in concreting forms, limited to size of 4 ft by 4 ft as average size. The outer bamboo stips strenght are when woven as in a mat. Several mat layers can be formed as wall panels, stiffened on one side by softwood boards. On the other hand, whole bamboo poles of thick variety can be connected by elongated nails,with end clamps. The practical pieces to be "nailed as such is 3 poles and can beome truss or beam parts. Bamboo is not good for posts as the buried portion o even embed in concrete footing easily dis-integrates or rut. Yes they are, at this time good only for 1 storey or low 2-storey structures, but high roofs are possible. Research must continue.

  3. Hyperman

    Great to see this research into renewable construction material. As Prof Lorna Gibson states for developing nations and communities the use of these materials could allow for cheaper housing and community centers, schools. I looking forward to my visit to Green Village in Ubud next month