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Super-Green Concretes Superseding Portland Cement


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Will Portland cement soon go the way of the dodo? There are good odds it might, as researchers around the world are looking for new ways to produce concretes that have a smaller carbon footprint and improved properties in terms of strength and durability.

In Malaysia, where green building is actively promoted by the Malaysian Government, researchers at the Universiti Teknologi MARA have developed “green mix concrete”.

The recipe includes fly ash — a waste product from coal burning power plants — and shredded fibres from used aluminium cans. It also utilises recycled concrete in the mix.

The recipe includes fly ash — a waste product from coal burning power plants — and shredded fibres from used aluminium cans. 

Fly ash has been established as a good substitute for Portland cement, and is increasingly used in concretes. In Malaysia, it used to be a source of pollution as it was generally disposed of in landfills or ponds. Aluminium cans are also a source of litter, and concrete waste from demolition sites frequently is sent to landfill.

The researchers found their Green Mix concrete is strong enough for commercial applications and is commercially viable in terms of costs to produce. To sweeten the pot, it also has a lower carbon footprint than traditional mixes.

At James Cook University in Queensland, PhD student Shi Yin and supervisor Dr Robin Tuladhar undertook research in collaboration with Queensland-based company Fibrecon into reducing the steel component of concrete’s footprint.

They are doing a pretty decent job, too. Their recycled polypropylene fibres produced from industrial plastic waste are actually strong enough to replace the steel mesh reinforcing used in footpaths.

The innovation won the team the Manufacturing, Construction and Innovation category at the 2015 Australian Innovation Challenge.

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

The recycled plastic also has obvious environmental advantages over using virgin plastic fibres,” Dr Tuladhar said. 

The plastic fibres were put to use on campus, in the construction of 100m-long footpath, and also in pre-cast concrete drainage pits designed by Fibercon.

At Melbourne University, researchers have produced a geopolymeric concrete that is quite similar to the concrete used by the Roman Empire in its buildings.

Instead of the calcium-based system of Portland cements, it uses an aluminium silicate system, where the key ingredients are sourced from industrial wastes. They include fly ash, blast furnace slag from iron-making plants, recycled concrete, recycled aggregates, and waste paper.

At Rutgers University in New Jersey, USA, Professor Richard E. Riman invented a concrete that stores carbon dioxide. The manufacturing process results in a concrete that reduces concrete’s carbon footprint by up to 70 per cent and water consumption by 60 to 80 per cent.

Instead of water, CO2 is used to cure the concrete — turning a problematic greenhouse gas into a valuable ally.

Professor Riman founded a company, Solidia Technologies, that is now producing a range of cement and concrete products using his patented processes.

Instead of water, CO2 is used to cure the concrete — turning a problematic greenhouse gas into a valuable ally. 

In October this year, the Oil and Gas Climate Initiative (OGCI) announced it was investing in Solidia Technologies. The OGCI is an initiative led by the CEOs of ten oil and gas companies, and it aims to collaborate on action to lead the industry response to climate change.

Its Climate Investments arm supports the development, deployment, and scale up of new technologies that will significantly reduce greenhouse gas emissions.

“We believe that Solidia Technologies’ product and process can provide a step change in lowering the greenhouse gas and water footprint of the cement and concrete industry,” OGCI Climate Investments CEO Dr. Pratima Rangarajan said.

“We are committed to helping them commercialise on a global scale to increase the adoption of their carbon recycling technology.”

Another manufacturer of green concrete that is seeing solid commercial success is Queensland-based company, Wagners. Their product has no No Portland cement in it. Instead, chemically-activated fly ash and slag are used in its place. The geopolymer “Earth Friendly Concrete” (EFC) has been used used in the carbon neutral Global Change Institute building in Brisbane.

It has also been used to construct a new airport, Wellcamp Brisbane West at Toowoomba. Fully-funded and owned by Wagners, the airport had geopolymer concrete used for the aprons, the buildings, and all other supporting infrastructure where concrete was required. More than 50,000 m3 of EFC was used for the project.

The company floated on the Australian Stock Exchange this month, with shares immediately jumping 25 per cent shortly after listing. 

The company floated on the Australian Stock Exchange this month, with shares immediately jumping 25 per cent shortly after listing. It plans to use the proceeds of the float to expand its share of the international cement market. Currently, it is the largest supplier in South East Queensland, with around 450 customers, including major commercial, civil, and residential contractors.

In October this year, Wagners EFC signed a Memorandum of Understanding (MOU) with $11b Indian conglomerate, JSW Group’s - JSW Cement. Wagners EFC director, Joe Wagner, said the MOU was a ground-breaking step towards an imminent joint venture between the two companies to produce EFC geopolymer concrete in India.

The Indian market produces more than 500 million m3 of concrete a year.

“This is a very exciting opportunity for us to partner with a company who has a similar attitude towards construction materials with carbon footprint reduction and is one of the country’s top cement producers,” Mr Wagner said. “JSW Cement is one of the leading brands in India and the joint venture will mean India can use our technology to recycle JSW’s steel and power production by-products.”

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