By Sara Nakasone
Bamboo is emerging as an alternative resource to other types of wood. In the past, people intuitively used it as a basic material for making many different household objects and small structures. However, ongoing research and engineering efforts are enabling us to realize bamboo's true value as a renewable, versatile and readily available economic resource. After briefly exploring the basic facts and traditional applications of bamboo, this article highlights the chemical and materials engineering behind the growth of reformed bamboo as well as the structural engineering issues involved in building larger and sturdier bamboo structures.
Tree stumps cry out to the harsh beat of the sun and birds torn from lost homes fly aimlessly in the sky. Rains sweep black sediment into rivers. These are just a few of the adverse environmental circumstances caused by the phenomenon of deforestation, which has resulted from society's demand for material resources. As resources deplete and the environment deteriorates, people are looking towards alternatives such as bamboo to replace conventional materials.
Bamboo is a giant grass commonly found in the tropical regions of Asia, Africa and South America. It comes in 1,500 varieties, from the popular household plant to ones that grow hundreds of feet tall. Bamboo is "the fastest-growing woody plant on Earth" ; it can reach maturity in months compared to other woods, which take decades. Bamboo is "a totally renewable resource;you can clear cut it, and it grows right back" .
Bamboo has been used in the eastern hemisphere for centuries. It is often labeled as the "poor man's timber" because developing countries in Asia, Africa and South America rely on it for food and as a building material. Bamboo can be used to provide shelter on a limited scale, mainly through its use in temporary and small structures. As environmental concerns rise, turning towards alternative sources is vital. Research is also being done to find ways to improve bamboo's structural capabilities to increase its value as a material resource. The increasing market for bamboo will hopefully also help stimulate growth in developing economies.
Applications of Bamboo
Historically, bamboo has been used to build numerous types of objects spanning from musical instruments to containers to housing frames. The "expanding movement in the West to start making better use of this amazing resource"  is expanding the market of bamboo. People all over the world are discovering innovative ways to use bamboo.
For centuries, bamboo has been used for scaffolds, temporary platforms that support construction workers while they do exterior work on a building, in places like China and Hong Kong (Fig.1). Though used minimally in China now, bamboo is still relied upon heavily in Hong Kong. It is an art form to build these 60 foot scaffolds; few have learned to lash poles tightly and how to "scamper up swaying scaffolds with long bamboo poles slung over their shoulders" . Many prefer bamboo scaffolds because they "bend in high winds, while steel scaffoldings break" .
On a smaller scale, bamboo is being used to build bicycles in Australia and Denmark. While a bicycle's basic design is almost flawless, there is much scope to improve the material it is made from. Conventionally, "light bicycles are made from aluminum, which is one of the most resource- demanding materials" in existence . Bamboo bikes are lighter than, and just as strong, as bikes made using aluminum. Moreover, bamboo is a more readily available resource.
During the 1980's, the International Development Research Center (IDRC) began to take note of people's reliance on bamboo. International wildlife expert Jane Stevens observes that strong IDRC support for bamboo research has resulted in funding to the tune of about 10 million dollars, used for national research programs involving more than 600 scientists and engineers in 14 nations . These studies and experiments have helped define the capabilities and strengths of bamboo, with the additional goal of improving bamboo to make it a more competitive resource.
One form of bamboo currently popular in the market is "laminated, or engineered bamboo lumber that makes gorgeous flooring, plywood and furniture" . There are different types of engineered bamboo on the market, the most developed of which is reformed bamboo.
In the future, reformed bamboo could fill some of the demand for industrial aluminum alloy. Aluminum alloy is an important resource used in making things like furniture, engines, rims and even the carrying case of Macintosh's newest laptop. Reducing the demand for aluminum alloy will help preserve the environment since lesser quantities of constituent metals will be extracted from the earth.
There are several variations of reformed bamboo being produced: the plain reformed bamboo (RB), the reformed bamboo/aluminum composite (RB/Al), and the reformed bamboo/glass fabric/aluminum composite (RB/GF/Al). The basic RB is crafted by splitting the bamboo lengthwise, then heating it to adjust the moisture of the material and soften it. The bamboo is then compressed and pressurized so that its pores contract and the moisture is set. RB/Al and RB/GF/Al are variations where aluminum and glass fabric are layered onto the sheets of the RB. While these variations have proven to be stronger than RB, the cost and time length of the production process tends to increase because of the added variants.
In the developmental phase of research and testing, reformed bamboo was shown to be stronger than normal bamboo. It is denser than normal bamboo, and thus contains more bamboo components within the same volume. This is analogous to comparing the density strength of a hollow tube and a solid tube; the hollow tube is brittle when compared to the solid tube. Due to its greater density, reformed bamboo is more flexible and compressible . RB/Al is stronger than both aluminum and reformed bamboo; the combination of the two creates a stronger material. RB/GF/Al is the sturdiest of all three variations because it absorbs the least amount of water under different conditions . With this ability to resist water, RB/GF/Al does not become saturated and weak. To use another analogy, a stiff piece of paper falls apart when it becomes drenched with water. All three types of reformed bamboo may be used in the future as a building resource.
"RB/GF/Al is an environmentally friendly material, more than 80% of its content being reformed bamboo, which is biologically regenerated. Reformed bamboo can be directly degraded; glass fabric and aluminum are also recyclable" . RB/GF/Al is the type of reformed bamboo with the most additives, yet it is environmentally friendly compared to other conventional resources. Therefore, using any of the three varieties of reformed bamboo as a construction material would help conserve precious resources.
Restraints on Use of Bamboo in Structures
As the advantages of bamboo become well known, people are attempting to experimentally build larger structures with bamboo. While there are many small and temporary shelters made of bamboo, researchers are now trying to build larger and sturdier homes. It is difficult for researchers to begin trial runs on bamboo homes due to existing restrictions placed by the International Congress of Building Codes (ICBO). "The ICBO has never established engineering criteria for the structural use of bamboo" . Due to a dearth of engineering studies and research regarding the strength and capabilities of different varieties of bamboo, it has been hard to establish common criteria for evaluating all bamboo. Studies have been done on certain kinds of bamboo; however there are 1,500 types of bamboo with varying characteristics. Clearly, establishing a uniform code for all bamboo is a formidable hurdle.
In Hawaii, people are trying to develop homes that are appropriate for the region, using bamboo specific to the area. Leimana Pelton, a renowned designer and builder of bamboo structures in Hawaii, comments about his crew working on bamboo homes: "We're trying to come up with practical and applicable solutions, which we believe are particularly appropriate for the lower Puna section, since if lava comes (down), these structures are easy to remove." There are several building codes that must be proposed, passed and put in place before bamboo can legally be used to construct new homes in Hawaii. Engineers at a company on the island of Maui have been testing different bamboo species to help establish the building codes. They have sent results to the ICBO and hope to get the codes implemented soon for these specific types of bamboo. With new building codes for bamboo, Hawaii will be the first American state to allow bamboo construction.
Developing Stronger Bamboo Homes
It is common to see small, temporary structures and furniture built of bamboo in developing nations. This is because "natural materials such as bamboo are available in abundant quantities in many developing countries, while conventional construction materials such as steel are not only expensive but also difficult to obtain" . Bamboo has a short life span if not treated; its high starch content causes insects to devour it.
Additionally, the grooves in bamboo collect water, making bamboo homes prone to saturation and mildew damage. Many countries, especially China and Costa Rica, have research teams developing new bamboo building designs that will be stronger than those that currently exist. The new homes are being developed to last longer and survive conditions like rain, winds and earthquakes.
In Costa Rica, engineers are developing safe ways to incorporate bamboo into household structures. The country sponsored a National Bamboo Project in 1986 as a "new technological approach to prevent deforestation in Costa Rica. The idea was to replace the use of wood with an alternative, cost-effective, and seismically-sound building material" . The team built 30 homes by using thick bamboo as a frame and then casing it with woven bamboo covered with mortar. These homes were put to a test when a 6.7 magnitude earthquake (same magnitude as the Northridge earthquake in 1994) rippled through Costa Rica with its epicenter being very close to the location of the homes. "Not one of the (bamboo) houses had a single crack" , while many other nearby structures collapsed.
The unique characteristics of bamboo allowed these structures to withstand the earthquake, while the heavy, inflexible concrete structures did not. The bamboo used in the National Bamboo Project could support 500 kilograms per square centimeter; this is nearly twice the strength of concrete . Handley adds that a top surface area of 10 square centimeters of this bamboo can support a 5000kg elephant . In addition, the bamboo's flexibility and light weight allowed the homes to "dance" with the earthquake until the waves ceased.
Benefits of Using Bamboo
Bamboo is environmentally friendlier than other types of wood. Bamboo is renewable, whereas other woods take hundreds of years to reach a mature stage. With bamboo replacing conventional lumber, fewer forests would have to be cut down for human consumption, thus reducing the greenhouse effect and other adverse environmental impacts of deforestation.
Using bamboo as a main construction resource will boost the market for bamboo and stimulate growth in developing economies. Bamboo is a strong and cheap construction material and more governments are investing in research to build safer homes for their people. Moreover, bamboo's light weight makes it favorable for construction and easy transportation.
Bamboo is a strong alternative material that is spawning a new worldwide trend towards renewable natural resources. When research and building codes for bamboo structures are successfully implemented, such structures will appear more commonly around the world.
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