Older building method could be key to sustainability and wildfire protection: UBCO

Old techniques get new life

Researchers at the University of British Columbia Okanagan are studying ways older building techniques could help improve construction stability and sustainability.

One of the methods UBCO researchers are looking at is "rammed earth" construction, which uses materials that are alternatives to cement and are often more readily available.

With international shortages in construction sand—which is much different than sand found on beaches—builders are searching for cheap, and readily available materials that are equally as strong, for next-generation cement.

"Everything old is new again and that is precisely why we’ve been investigating rammed earth construction,” says Dr. Sumi Siddiqua, with UBCO’s School of Engineering. “By integrating industrial by-products, we’re addressing an increasing need for readily available building materials and being sustainable in the process.”

One such alternative is wood fly ash, a by-product of pulp mills and coal-fired power plants.

The construction industry has been trying to find a use for materials like fly ash that predominantly ends up in landfills. Fly ash, better described as a fine powder, shares the same strength and texture characteristics as cement, which is often added to concrete to enhance its strength.

“There are many benefits to using this material. Using local soil along with rammed earth products reduces sand exploitation. And just as importantly, this material is not affected by wildfires to the same extent as current wooden structures,” says Siddiqua.

UBC’s Build Better Cluster, together with BC Housing, is teaming up with Indigenous communities to integrate rammed earth into the construction of new homes.

Test results show that, under most circumstances, fly ash enhances the structure’s properties and makes it suitable for use in cold and hot climates as load-bearing, non-load-bearing and isolation panel walls. Fly ash is also available in remote communities and provides increased insulation properties.

There may not be an immediate uptick in the construction of rammed earth homes and buildings but adding materials like fly ash into composite cements has already begun.

“There is an increasing demand for sustainable building products here in Canada and around the world, and materials like fly ash are just the start of a new and important trend,” Siddiqua says.

A prime example of rammed earth can be found at the 'Bernard Block' in downtown Kelowna. At the midpoint of the building, on the ground floor, is a rammed earth wall that rises just over 55 feet. Another example can be found at the Spirit Ridge at Nk'Mip Resort, in Osoyoos.

The research was published in the latest edition of the Journal Construction and Building Materials.

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