Team creates sustainable bricks from waste

A team of engineers at Australia’s RMIT University has created energy-efficient bricks derived from waste that promise to reduce electricity bills by 5%. That also means a 20% reduction on firing temperatures for manufacturers, by replacing clay with waste materials in the production of this new brick material.

Working in conjunction with Australia’s largest recycling company Visy — which reportedly recycles around 512,000 tons of glass containers and bottles and remanufactures them into 3.2 billion bottles and jars every year — the RMIT University team created the recipe for these sustainable bricks.

Source: RMIT University

Specifically, unwanted materials destined for waste disposal — waste glass and combustion byproducts, for instance — were selected as the ingredients for the new brick material. The researchers explained that they used roughly 15% waste glass and 20% combusted solid waste or ash as substitutes for traditionally used clay.

Noting that the manufacture of traditional bricks produces harmful emissions — including carbon dioxide (CO₂), sulfur dioxide and chlorine — the researchers wanted to reduce the strain on natural resources like clay.

To create the bricks in the lab, the team used a pulverizer to smash clay soil to a requisite size. The clay and RCF wastes were then dried for 24 hours in a bid to remove moisture. Once dried, the material was mixed with water and then it underwent compaction. The team avoided the cracking associated with water evaporation during the firing process by initially drying the bricks in air for two days and then oven-drying them for 24 hours following the compaction process. Finally, the bricks were fired in the furnace resulting in bricks that satisfied all of the standards related to structure, durability and environmental sustainability.

The team concluded that bricks manufactured using this approach demonstrated 24% lower thermal properties than regular bricks. Likewise, these bricks require 10% lower temperature to fire, which reportedly translates to a reduction of 417 tons of CO₂ emissions.

The study, “Utilizing rejected contaminants from the paper recycling process in fired clay brick production,” appears in the journal Construction and Building Materials.

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