Reinforcing concrete with recycled plastic
A new method for replacing steel mesh used in concrete reinforcement with recycled plastic has seen Queensland engineering firm Fibercon recycle over 50 tons of plastic waste. While plastic fibres in concrete have been around for 20 years, Fibercon’s process is said to be the only one that uses 100% recycled material.
Developed in conjunction with researchers from James Cook University (JCU), the technology uses recycled polypropylene plastic for reinforcing concrete instead of the traditional steel, resulting in reduced CO2 emissions, water usage and fossil fuels. Since its first use in 2017, the technology has been incorporated into Fibercon’s Emesh product primarily for use by councils in footpaths, but it also has applications from pavement concrete to channel drains, embankment erosion control, precast sewer and stormwater pits.
Around 1.6 billion tons of steel are produced worldwide every year, making steelmaking one of the world’s leading industrial sources of greenhouse gases — one that is also heavily dependent on fossil fuels and water. The process makes steel from iron ore by heating it with carbon, predominantly coal; carbon dioxide is produced as a by-product. Production of a ton of steel generates almost two tons of CO2 emissions, accounting for as much as 5% of the world’s total greenhouse-gas emissions.
Steel reinforcement in concrete — or rebar — was meanwhile introduced in the mid-18th century as a means of improving the tensile strength of concrete, and is now the most commonly used form of concrete. With concrete use at approximately 1 m3 per person, Australia uses 25 million m3 of concrete per year, at least 5% of which is footpath and light pavements.
“If we replaced all the steel mesh in these pavements with Emesh, we would reduce our CO2 by 125,000 tons annually, and re-use 5000 tons of waste plastic,” said Fibercon CEO Mark Combe.
Meanwhile, Australia averages 107 kg of plastic waste per person each year, according to a report prepared for the Department of the Environment and Energy in 2016. The 50-ton milestone therefore means that Fibercon has effectively recycled the plastic waste of 467 Australians, Combe noted — in addition to reductions of 1000 tons of CO2, 200 tons of fossil fuels and 18,000 m3 of water.
“According to the United States Environmental Protection Agency calculations, the reductions we have achieved in CO2 emissions are the equivalent of taking 214 passenger cars off the road for one year,” said Combe.
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