GIVING NEW MEANING TO S#!&*ING BRICKS

Using recycled or ‘green’ building materials is a growing trend in today’s housing industry, with many developers and homeowners making a conscious effort to choose materials that support a cleaner environment through manufacturing processes and eliminate emissions post production. The latest development, turning biosolids into bricks, could be a significant advancement in this industry.

A university research team from RMIT, who published their findings in the January issue of Building journal, are working on a way to recycle biosolids - organic matter recycled from sewage – into bricks, repurposing the world’s stockpiles of wastewater treatment by-product to create greater sustainability in the construction sector.

“About five million tonnes of the biosolids produced in Australia, New Zealand, the EU, US and Canada currently go to landfill or stockpiles each year. Using a minimum 15 percent biosolids content in 15 percent of bricks produced could use up this five million tonnes,” claims Professor Abbas Mohajerani from RMIT University.

With approximately 30 percent of the world’s biosolids stockpiled or sent to landfill, according to Professor Mohajerani, the environmental challenge created by this practice could be negated with a sustainable solution that impacts both wastewater treatment and clay brick manufacturing – which requires the use of a lot of fuel to generate the heat required to produce bricks, making it environmentally undesirable. Currently, more than three-billion cubic metres of clay soil is dug up each year for the global brick making industry, producing approximately 1.5 trillion bricks.

The university team developing this technology has demonstrated that fired-clay bricks that incorporate around 25 percent biosolids only require half the energy of conventional bricks to produce, making them cheaper to manufacture. Biosolids bricks also present substantial benefits due to their lower thermal conductivity, which means higher environmental performance in buildings.

The researchers found that biosolid-enhanced bricks passed compressive strength tests and analysis demonstrated heavy metals are largely trapped within the brick. Though further testing is required to find the most effective biosolid composition, Professor Mohajerani hopes that government building codes could confidently mandate a conservative 15 percent biosolids component in house bricks in the near future – tackling two environmental issues at the same time; biosolid stockpiling and the excavation of billions of cubic metres of clay soil each year.

Image RMIT University