Image credit: Swiss National Science Foundation (SNSF)Image credit: Swiss National Science Foundation (SNSF)Combining wood and concrete in the construction of buildings is nothing new. What is new, according to Swiss researchers, is the approach to combining wood and concrete to create a load-bearing concrete consisting of mostly wood.

Traditionally, the combined materials have been used for non-load-bearing purposes (like insulation). But researchers are beginning to imagine a different purpose for wood-based concrete.

Daia Zwicky, head of the Institute for Building and Environmental Technologies at the School of Engineering and Architecture of Fribourg, discovered through a battery of tests that traditional concrete differed from the wood-based concrete in terms of makeup. Traditional concrete is made of gravel and sand while finely ground wood (sawdust) makes up the wood concrete mixture.

“They weigh at most half of what normal concrete weighs – the lightest of them even float!" said Zwicky.

The new combination of wood and concrete acts as a thermal insulator and also offers flame retardance. Additionally, the concrete can also be reused as a source of heat and electricity once dismantled because of its high wood content. (However, the material conforms to fire protection standards.) The material is also suitable for slab and wall elements and can offer a load-bearing function in construction.

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