Ann-Cathrin Jöst, BBA & MSc

Throuhgout the last years, bamboo has been engineered into various products. Due to its fast growth and its tensile strenght, I frame engineered bambo as a niche resource that directly competes with timber. With my Master thesis, (you can request it and a consultancy for a fee), I concluded that bamboo boards outweight timber products made from oak, maple, walnut, birch and cherry in terms of its strength properties and durability. Likewise, engineered bamboo outweights timber in terms of its properties and is perceived as an excellent building material, if it is less visible or more available with greater design variance.

How does bamboo compare to other construction materials?

Cement, concrete, aggregates, metals, bricks, clay are the most common types of non-renewable resources used in construction. Next to these natural materials, wood is also used frequently (Wang, 2018).

Cement, is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. There is no present bamboo cement replacement.

Concrete and cement are often used interchangeably, cement is actually an ingredient of concrete. Concrete is a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and  cement. While it is not possible to fully replace concrete with bamboo, it is possible to produce bamboo reinforced concrete (Karthik et al., 2008)

Currently  steel reinforcement is used frequently to provide additional tensile strength and energy absorption capacity to concrete members. But conventional M.S. (Mild steel) or HYSD (High Yielding Strength Deformed) bars are heavy in weight, costly, nonrenewable and un-ecofriendly material. To mitigate this concern a sustainable, renewable, ecofriendly material like bamboo can be used as steel substitute. Using bamboo reinforcement can improve the flexural performance of slab panels (Mali and Datta, 2018).

However Archila, Kaminski, Trujilo, Escamilla and Harries (2018) describe that “the poor durability and bond characteristics of bamboo require through-thickness treatment and additional surface treatment of bamboo reinforcement, respectively. Such treatments, as described in the literature, are labour intensive, costly, and often utilise materials of known toxicity .”

Metals are commonly used in the construction industry due to their durability and strength to form structural components, pipework, cladding materials and other components.

Bamboo is stronger than the metal steel, in regards to the tensile strength. Overall, the ratio of tensile strength between the weight of bamboo is six times greater than of steel. If treated and processed well, buildings can be fully engineered with bamboo. As highlighted above, bamboo can be used as concrete reinforcement and steel alternative.

Construction aggregate, or simply “aggregate”, is a broad category of coarse to medium grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates such as sand are the most mined materials in the world. According to the World Economic Forum (2019), between 32 and 50 billion tonnes of aggregate (sand and gravel) are extracted from the Earth each year. Excessive sand mining of river deltas, such as the Yangtze and Mekong, is increasing the risk of climate-related disasters, because there’s not enough sediment to protect against flooding.

In Manlapas, Cardenas and Anacta (2018) study, they produced concrete samples with 1% and 3% bamboo fibers as additives. It was concluded that the addition of bamboo fiber increases the compressive strength of concrete. Substituting coarse aggregates with certain percentage of bamboo fiber produced a decreasing trend on its flexual strength, though it increased as the bamboo fiber composition/materials increased.

Another study incoroporated bamboo ash into fly ash geopolymer concrete. It concluded that bamboo ash can be one of the alternatives to geopolymer concrete when it faces exposure to high temperatures.

Bricks are still in common use today for the construction of walls and paving and for more complex features such as columns, arches, fireplaces and chimneys. They remain popular because they are relatively small and easy to handle, can be extremely strong in compression, are durable and low maintenance, they can be built up into complex shapes and can be visually attractive.

I found only one website that sells” bamboo bricks” , but it does not describe the content of the bricks. Another study applied bamboo waste material (charcoal) on ecobricks.

Different types of wood and wood materials are also used for the construction of buildings. The company SwissKrono, produces prefabricated timber construction and uses a mix of timber and non timber material on project base. Solid timber constructions involve prefabricated sturby but relatively lightweight walls, ceilings and roof modules that are assemblied on the construction site. Other materials include the construction frames which are stabilised with OSB panels. There are also penalised constructions, in which walls and ceilings are largely prefabricated.

These type of constructions can also be produced from bamboo and likely outweight timber due to its lightweight, strength and hardwood characteristics. In addition, bamboo already matures within three to five years and could therefore serve as an alternative resource next to controversial produced timber , particular from the tropics.

A barrier for a fully ecological bamboo utilzation is the type and the amount of chemicals used for the production of engineered bamboo products. If bamboo products are produced in closed loop systems or if bio-based resins are used, bamboo could serve as a sustainable and circular building opportunity. Another option would be to produce modular bamboo buildings or components, that can be re-used at the end of the buildings life cycle.

Conclusion

The future of the bamboo building industry looks promosing, particular as a result of bamboo being a strong and lightweight material. However, at the moment, it seems difficult to replace conventional building materials such as cement, concrete and aggregates with bamboo. The main potential of bamboo remains in being an alternative to steel as bamboo composite material and as major structural support for buildings. Bamboo also holds huge technical potential as “background matrial” (i.e. MDF/OSB plates/ foundation).

Questions? Please contact me.

References

Archila, H., Kaminski, S., Trujillo, D., Escamilla, E. Z., & Harries, K. A. (2018). Bamboo reinforced concrete: a critical review. Materials and Structures, 51(4), 102.

Global Status Report (2017). World Green Building Council. Retrieved from:  http://www.worldgbc.org.

Jöst, A. (2019). Bamboo in German Manufacturing Practices. Master Thesis. Maastricht University

Hutt, R. (2020). This is the environmental catastrophy, you probably never heard of. World Economic Forum. Retrieved from: https://www.weforum.org/agenda/2019/04/global-demand-for-sand-is-wreaking-havoc-on-rivers/

Karthik, S., Rao, R. M., Awoyera, P., Akinwumi, I., Karthikeyan, T., Revathi, A., … & Saravanan, S. (2018). Beneficiated pozzolans as cement replacement in bamboo-reinforced concrete: the intrinsic characteristics. Innovative Infrastructure Solutions, 3(1), 50.

Mali, P. R., & Datta, D. (2018). Experimental evaluation of bamboo reinforced concrete slab panels. Construction and Building Materials, 188, 1092-1100.

Manlapas, G. O., Cardenas, L.E., Anacta, E.T. (2018). Utilization of Babmoo Fiber as a Component Material in Concrete. Indian Journal of Science and Technology. 11(47).

Wang, T. (2018). Construction Materials Industry. Retrieved from: https://www.statista.com/topics/2983/construction-materials-industry/