Australasian Science: Australia's authority on science since 1938

Plastic Toughens Concrete

Concrete is the second most-used material in the world, being second only to water. More than 25 million cubic metres of concrete are poured annually in Australia.

Cement prod2uction produces 900 kg of CO2 for every tonne of cement, and is responsible for 5% of total annual global CO2 production.

Now, however, the environmental cost of concrete could be drastically reduced after engineers swapped steel reinforcing for plastic waste.

Dr Rabin Tuladhar of James Cook University found that short pieces of recycled plastic can be added as reinforcement in concrete, removing the need for steel mesh in concrete footpaths and precast elements such as drainage pits and concrete sleepers.

“Using recycled plastic, we were able to get more than a 90% saving on CO2 emissions and fossil fuel usage compared to using the traditional steel mesh reinforcing,” Tuladhar said. “The recycled plastic also has obvious environmental advantages over using virgin plastic fibres.”

In 2013 Australia’s total consumption of polypropylene plastic was around 220,000 tonnes, from which only 21% was recycled.

Tuladhar’s team has conducted successful strength and durability tests on the pre-cast concrete elements made with the recycled plastic fibres. They are now consulting with concrete producers and local and federal governments about how to employ the new findings.

Tuladhar’s work has focused on making concrete production more sustainable. It includes the replacement of natural sand with crusher dust (a by-product of stone quarries) and the replacement of cement with up to 30% mining waste.