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Bricks from waste mooted to boost sustainability


Fired-clay bricks incorporating biosolids could solve the construction sector’s sustainablity woes, researchers have claimed. 

The research, conducted by a team at RMIT University in Melbourne, Australia, prompted the suggestion that the world’s stockpiles of treated sewage sludge could be recycled to boost sustainability in construction.

Biosolids are a by-product of the wastewater treatment process that can be used as fertiliser in land rehabilitation or as a construction material.

Approximately 30% of the world’s biosolids are stockpiled or sent to landfill, and therefore use up valuable land while potentially emitting greenhouse gases.

Published this month in the journal Buildings, the RMIT University team’s research claims that producing biosolid bricks requires around half the energy of conventional bricks.

The research examines the physical, chemical and mechanical properties of fired-clay bricks incorporating between 10% and 20% biosolidmaterial.

In addition to being cheaper to produce, the biosolid bricks also have lower thermal conductivity, transferring less heat. As a resul they could improve the environmental performance of buildings.

Associate professor Abbas Mohajerani, who was the lead investigator, said the research aimed to address two environmental issues – stockpiles of biosolids and excavation of soil required for brick production.

Mohajerani, a civil engineer in RMIT’s School of Engineering, said: “More than 3bn.mof clay soil is dug up each year for the global brickmaking industry, to produce about 1.5 trillion bricks.

“Using biosolids in bricks could be the solution to these big environmental challenges. It’s a practical and sustainable proposal for recycling the biosolids currently stockpiled or going to landfill around the globe.”

The European Union produces over 9M.t of biosolids annually, while the United States and Australia produce 7.1M.t and 327,000t per year respectively.

The RMIT University team’s research also shows that brick firing energy demand was cut by up to 48.6% for bricks incorporating 25% biosolids, due to the organic content of the biosolids. Such findings could therefore reduce brick manufacturing companies’ carbon footprint.

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