Science & Technology

Cross Laminated Timber (CLT) made from Rubber Wood, Coconut Wood, and Oil Palm Wood? Perhaps you're familiar with it, or perhaps not. So, what exactly is it? 

CLT is a type of engineered wood product created by stacking and gluing wooden layers in perpendicular positions, typically consisting of 3, 5, and 7 layers. It is known for advantages such as design flexibility, carbon sequestration, lightweight properties, good insulation, rapid construction, and environmental friendliness. 

In Thailand, the usage of CLT is still not widespread. However, mixed species/density CLT made from Rubber Wood, Coconut Wood, and Oil Palm Wood is being developed at Walailak University by Associate Professor Dr. Suthon Srivaro, a researcher at the Center of Excellence in Wood and Biomaterials, School of Engineering and Technology.

The project is in collaboration with The University of British Columbia (Canada) (Prof. Dr. Frank Lam and Assoc. Prof. Dr. Minghao Li), Seoul National University (South Korea) (Assoc. Prof. Dr. Jung-Kwon Oh), University of Canterbury (New Zealand) (Dr. Hyungsuk Lim and Assoc. Prof. Dr. Clemens Altaner), University of Sopron (Hungary) (Dr. Zoltan Pasztory), and Nakhon Si Thammarat Rajabhat University (Thailand) (Asst. Prof. Dr. Sataporn Jantawee). It is supported by the National Research Council of Thailand and Walailak University through the funding scheme “Mid-Career Researcher grant” (Contract No. N42A650375).

Figure 1 Configurations of 5-layer CLT [1]

Dr. Suthon mentioned that his interest in developing the CLT stems from the fact that there are plenty of Rubber Trees, Coconut Trees, and Oil Palm Trees available within Thailand as well as around the tropical zone. After the trees reach the end of their lifespan and can no longer be productive, they will be cut down.

"So, instead of just selling the tree trunks or letting the trees decompose naturally in the environment, we can create high-value-added mass timber products from these wood species for the construction market, offering an eco-friendly alternative to concrete and metal." 
 

Figure 2 Rubber, Coconut, and Oil Palm regarded as key economic crops in Thailand

Dr. Suthon further explained that, nowadays, wood has become an alternative material for building construction due to its positive impact on the environment and high structural performance. In many countries, CLT is an innovative engineered wood product widely used as load-bearing walls and floors in mid- and high-rise building construction. 

“Developing engineered wood products from wood species available in Thailand could increase their economic value and promote the green building industry in line with the United Nations’ Sustainable Development Goals,” he added.

Figure 3 The 18- storey CLT building constructed in Vancouver, Canada (Source: www.thinkwood.com)

Dr. Suthon highlighted that when the team first planned to develop a new type of CLT product for the market, its properties and price were basically concerned. So, instead of using a single species, the team proposed developing mixed-species CLT to promote the utilization of relatively expensive but high-performing species alongside economical but low-performance species.           

Figure 4 Coconut CLT (Left) and Mixed-species CLT from Rubber Wood and Coconut Wood(Right)[2-4]

“For oil palm wood, however, it is not suitable for use as structural timber due to its relatively low strength. Thus, we need to improve its properties first. Recently, we have successfully improved the properties of oil palm wood through thermal compression. We found that the resulting wood had comparable properties to structural timber, which could be further used for mass timber products,” said Dr. Suthon.

Figure 5 Schematic drawing of thermal compression (Left) and the original and thermally compressed oil palm wood (Right) [5-6]

Although research on CLT in Thailand is still in early stages, Dr. Suthon mentioned that if collaboration between the academic, government and industries is properly set, this material could be pushed into the construction market in the near future. 

At present, the Center of Excellence in Wood and Biomaterials, School of Engineering and Technology, has successfully created a prototype building made of coconut wood-based CLT, located at Koh Yai Grand Canyon Park, Songkhla Province. The team plans to continue their research and aims for the future use of CLT in construction market in the country.
 

Figure 6 CLT Prototype Building at the Center of Excellence in Wood and Biomaterials, Walailak University (left), and Figure 7 Walailak University's CLT Building, situated in Koh Yai Grand Canyon Park, Songkhla Province (right).

References:
[1] FPInnovations. (2013). CLT Handbook US Edition.
[2] Srivaro, S., Pásztory, Z., Le Duong, H. A., Lim, H., Jantawee, S., & Tomad, J. (2021). Physical, mechanical and thermal properties of cross laminated timber made with coconut wood. European Journal of Wood and Wood Products, 79(6), 1519-1529.
[3] Wang, K., Lim, H., Li, M., Srivaro, S., & Oh, J. K. (2023). Effects of density and load orientation on embedment behaviour of coconut wood. Construction and Building Materials, 371, 130736.
[4] Srivaro, S., Lim, H., Li, M., & Pasztory, Z. (2022). Properties of mixed species/density cross laminated timber made of rubberwood and coconut wood. Structures, 40, 237-246.
[5] Srivaro, S., Lim, H., Li, M., & Altaner, C. (2022). Effect of pressing parameters on dimensional stability and bonding performance of thermally compressed coconut wood. Construction and Building Materials, 357, 129359.
[6] Tomad, J., Srivaro, S., Lim, H., Li, M., Oh, J.K., (2024). Characteristic properties of thermally compressed oil palm wood and its potential for glued laminated timber products. Industrial Crops and Products, 216, 118757.