Understanding bamboo's thermal and mechanical properties to design fire-resistant buildings

Natural materials such as bamboo can be utilized to construct fire-resistant and safe buildings.

Currently, construction industry uses materials (steel and concrete) that are environmentally inefficient. As a result, 30-40% of the global CO₂ emissions derive from building infrastructure. In an effort to reduce humanity's environmental footprint, natural materials could replace concrete and steel without reducing the structure's integrity.

Bamboo is considered a sustainable material that can be used for energy-efficient infrastructure. Understanding and quantifying its properties is essential to be implemented in design and construction projects. A new study, recently published in the journal Scientific Reports, provides new data about the thermal conductivity of bamboo.

Researchers studied the thermal properties of bamboo by applying advanced scanning thermal microscopy. In particular, the team focused on the vascular tissue (which transports nutrients and fluids) of bamboo and found out that its structure consists of a network of thin and thick cell walls. Thick layers account for the material's high thermal conductivity, stiffness and strength whereas thinner layers have lower thermal conductivity.

This finding shows that heat travels through the thick layers of bamboo, a fact that completely affects the material's behavior when exposed to fire. The new information can be used in modeling its thermal response and to suggest appropriate measures to increase its safety. “People may worry about fire safety of bamboo buildings. To address this properly we have to understand the thermal properties of the building material. Through our work we can see that heat travels along the structure-supporting thick cell wall fibers in bamboo, so if exposed to the heat of a fire the bamboo might soften more quickly in the direction of those fibers. This helps us work out how to reinforce the building appropriately,” Dr. Darshil Shah, lead author of the study and a researcher in the Department of Architecture, Cambridge University, stated.

Until today, bamboo has been mostly used as a flooring material as it is durable and hard. Nevertheless, authors suggest that it can also be used as a building material due to its high stiffness and strength. 

Wood has already been utilized in building infrastructure and mostly includes the usage of cross-laminated timber, a material processed to obtain a similar structure with bamboo. “Cross-laminated timber is a popular choice of timber construction material. It’s made by gluing together layers of sawn timber, each at a right angle to the layer below. Seeing this as a natural structure in bamboo fibers is inspiration for the development of better building products,” Dr. Shah, added.

The research team concludes that scanning thermal microscopy will be a powerful tool and will provide new insights into plant science.

Source: University of Cambridge