Study of cross-laminated timber panels behavior

Researchers from the University of Arkansas will study the behavior of cross-laminated timber panels installed in the new residence hall of the campus.

The response of cross-laminated timbers (CLTs) as a construction material has not been thoroughly investigated. Currently, scientists will study the behavior of the installed panels focusing on measuring the moisture change.

CLT is made out of planks of layered wood where each layer is placed perpendicular to the previous one. Using this technique, there are no weak planes and the material gains both compressive and tensile strength in all directions.

According to Tahar Messadi, principal investigator and Associate Professor of Architecture and the 21st Century Chair in Sustainability in the Fay Jones School, CLTs are strong yet lightweight materials and have great fire, thermal and seismic performance. Moreover, they are easily installed and produce bare minimum waste. 

The researchers will focus on analyzing the water content in CLT panels as it is a critical factor associated with the material's behavior. Normally, the moisture content of a CLT panel must range between 9%-15%. An increase in moisture will affect the mechanical properties of the material as it will lead to loss of strength and stiffness and may cause steel connections to rust. Moreover, wood is also prone to mold and fungus when the water content is high. “Anything higher than 20 percent would be susceptible to surface fungal attacks and higher than 25 percent would compromise the structural integrity of the timber through decay and rotting,” Prof. Messadi said.

The effects of weather and humidity on the CLTs will be detected via 135 specific sensors that are installed in the panels with the focus on those in the most prone areas (kitchen, bathrooms and outside of the building). Every sensor will record the moisture content every half an hour and the data will be sent to a server. The procedure will last for 2 years. “Our aim is to find out whether a stable reading is maintained throughout the two years or not. Once we look at that data, we will then understand the sort of remedies we will be able to bring forward to make sure that the CLT behaves in the right way and in the right setting, according to newly developed standards,” Prof. Messadi added.

Arkansas state timber production is the 3rd among the U.S. If CLTs were widely used in the construction industry, the economy would be highly boosted and the environmental footprint would be significantly reduced. “Mass timber is interesting because, not just in Arkansas, sustainability is a growing issue in the construction industry. Concrete and Portland cement are hard on the environment. They can release a lot of carbon dioxide, whereas wood is a renewable resource. In Arkansas, we have an underutilized timber industry, so it’s a potential opportunity in the state to make panels here, or sell our lumber to places that make panels,” Cameron Murray, co-investigator and Assistant Professor of Civil Engineering at the University of Arkansas, stated.