Creating wood-based concrete

A new type of concrete that largely consists of wood and based on renewable resources has been developed, offering the construction industry new avenues and possibilities. Photo credit: Swiss National Science Foundation

Houses in the past were made of wood, and many examples still stand today. But now, two building methods are being increasingly integrated to create hybrid structures which contain elements of both concrete and wood, a popular path in contemporary architecture, much like Shigeru Ban’s Terrace House.

Now, Swiss research scientists under the National Resource Programme “Resource Wood” have developed a more radical approach in combining concrete and wood, fabricating concrete that is made up largely of wood, and capable of bearing loads. Altogether, the volume fraction of the wood is more than 50 per cent.

While wood products bonded with concrete have been around for over a century, they were only used in non-load-bearing ways, like insulation. But Daia Zwicky, head of the Institute for Building and Environmental Technologies at the School of Engineering and Architecture of Fribourg, Switzerland, pondered if the use of concrete based on wood could be used more ambitiously.

Together with his team, Zwicky explored the possibilities with the content and granularity of the wood along with diverse additives, replacing the gravel and sand in concrete with wood, and later put the blends through robust tests. Due to the high wood content, the new building materials are more flame resistant while also acting as thermal insulators, and the wood, while conformed to fire protection standards, can be later reused as waste incineration.

“They weight at most half of what normal concrete weighs – the lightest of them even floats!” Zwicky enthused to the Swiss National Science Foundation (SNSF).

Additionally, the materials are largely based on renewable resources, and can be reused as a source of heat and electricity even after dismantling.

Initial tests have shown that the new material is also suitable for slab and wall elements, and is capable of offering a load-bearing function in construction, though the researchers wish to subject the wood-based concrete to more tests in order to broaden their expertise and find out which wood-based concrete composite is best for a variety of applications, and how they can be produced on an effective and efficient scale.

“It will take several years before we see the first buildings in which lightweight concrete containing wood plays an integral role in construction,” Zwicky said. “The level of knowledge required for widespread application is still too limited.”

 

Source: Swiss National Science Foundation