Geopolymer concrete laid in Sydney

Geopolymer concrete, made with industrial waste from coal-fired power stations and steel manufacturing, is being used for a green roads trial in the City of Sydney.

New concrete has been laid on a busy inner-city street, replacing a 30 metre section of roadway on Wyndham Street in Alexandria.

To test the concrete’s durability, the city has laid 15 metres of traditional concrete and 15 metres of the geopolymer concrete.

Nine sensors have been positioned to monitor and compare how the geopolymer concrete performs.

Sydney Lord Mayor Clover Moore said UNSW Sydney researchers and the CRC for Low Carbon Living will use trial results to create the first set of industry guidelines for geopolymer concrete.

“Local governments are responsible for maintaining local roads, so if we can purchase more environmentally sustainable materials, we can fight climate change and provide quality infrastructure for our community,” Ms Moore said.

“With 70 per cent of the concrete produced today going into pavements and footpaths, there’s great potential to further lower emissions from our operations.”

Made from fly ash and blast furnace slag, geopolymer generates 300 kilograms of CO2 per tonne of cement, compared to the 900 kilograms from traditional cement production.

“We’re continually working with concrete suppliers to reduce the amount of pollution and greenhouse gases emitted during the production of concrete for our local roads,” Ms Moore said.

“We already use sustainable green concrete for all our footway renewal works – which adds up to 25,000 metres squared per year.”

According to Ms Moore, the low CO2 concrete has the potential to reuse 400 million cubic tonnes of globally documented waste from the coal and steel industries.

Australian Iron and Steel Association and Ash Development Association Executive director and industry partner Craig Heidrich said the benefits of the trial will be far-reaching.

“Our collaboration with organisations such as the City of Sydney and the publication of the research findings will further demystify and promote the use of geopolymer concrete in construction,” Mr Heidrich said.

“It’s a fundamental tenet in business that you need to be constantly innovating and investing into new technologies. This trial will provide real examples of geopolymer concrete use that we can all use.”

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Tyre Stewardship invests in crumb rubber concrete

The University of South Australia, with funding from Tyre Stewardship Australia, is working to develop and test reinforced crumbed rubber concrete (CRC), for use in the residential construction industry.

CRC is made by replacing sand with crumb rubber, from end-of-life tyres, in concrete mixes.

Tyre Stewardship CEO Lina Goodman said the University of South Australia testing has assessed both the material itself and its structural properties, with encouraging results.

“Nearly 40 per cent of the annual total of approximately 9.6 million cubic metres of Australian pre-mixed concrete is used for residential construction,” Ms Goodman said.

“That volume presents a significant opportunity to consume very substantial quantities of recycled rubber, and could account for a large proportion of the 56 million end-of-life tyres Australia generates each year.”

According to Ms Goodman, CRC showed no difference in performance when compared with conventional concrete during a full-scale trial of residential slabs.

“There were no issues related to the mixing and delivery of CRC by a commercial ready-mix supplier, and the residential slab contractors working with the new product reported easy application and no difference when finishing the concrete surface,” Ms Goodman said.

“In addition, as with conventional concrete, no visual deterioration was observed on the rubber concrete slab surface after three months. All the initial results indicate that CRC in residential slabs is a promising and potentially viable alternative to conventional concrete.”

Ms Goodman said the commercial potential for CRC is considerable, with positive properties including increased toughness and impact resistance, reduced tendency for cracking and shrinkage and better acoustic and thermal insulation.

“Given the ongoing population growth that is sure to sustain a growing domestic construction industry, the work we are supporting on the development and testing of CRC is one of the most promising areas of market development,” Ms Goodman said.

“Ultimately, the aim is to find valuable uses for tyre-derived material that generate a strong domestic market, create a value for the resource and, in that way, deliver a sustainable circular economy outcome.”

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Footpath trial of recycled plastics in Lake Macquarie

Lake Macquarie City Council has used glass sand and recycled plastics on 30 metres of footpath as part of a project trialing the use of environmentally sustainable material.

‘Greencrete’ contains crushed glass sand and polypropylene strips made from 100 per cent recycled plastic which helps reinforce the concrete in place of steel mesh.

Manager of Lake Macquarie Asset Management Helen Plummer said 50 per cent of the fine aggregate used in the concrete was manufactured with glass sand rather than virgin material.

More than 5000 tonnes of glass is collected from Lake Macquarie homes each year, with a portion being sent to a Central Coast processing plant where it is washed and crushed into sand.

“We conducted extensive testing on the concrete prior to it being poured and it is a case of so far, so good.

“We will continue to monitor the footpath in coming months to see how it holds up to everyday wear and tear, and whether it cracks or wears differently to normal concrete,” Ms Plummer said.

Lake Macquarie council began trialling the use of recycled glass sand in civil works projects last June using the material in underground drainage pits.

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Victorian recycling research and development grants now open

Sustainability Victoria has opened applications for Research, Development and Demonstration Grants of up to $200,000 for projects that can increase the quality of recycled products sold in Victoria.

Businesses, local governments and researchers can apply for grants between $50,000 and $200,000 to help stimulate markets for products made from recovered resources.

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Projects that investigate one or more materials which have specific supply or demand side barriers which could be overcome with support from the government are encouraged to apply.

Concrete and brick, electronic waste, glass, organic material, paper and cardboard, plastics, rubber and textiles have all been identified as targeted materials for the grant.

The grants have been designed to support the industry in commercialising new products and processing approaches and to increase the end market uptake and demand for the targeted materials.

Successful applicants will have their projects matched dollar for dollar by the state government.

Previous research projects included alternative uses for glass fines and flexible plastics in construction and manufactured products, such as railway sleepers, plastics in concrete footpaths, glass in non-load bearing concrete and roof tiles made from glass waste.

Sustainability Victoria CEO Stan Krpan said the grants would increase job creation, develop quality products for end markets and increase investment in products made from recovered resources.

“Recent shifts in the current international recycling in gives Victoria greater impetus to develop local markets for the products we can recycle,” Mr Krpan said.

“It is crucial such markets are developed so the value of recovered resources is realised.

“This funding provides industry the opportunity to develop and trial new or existing products and specifications that use significant and reliable quantities of targeted materials,” he said.

The program will also inform the industry of the possible opportunities to use recovered materials in manufacturing to support using products made from recycled content.

“Recycling is an increasingly important community issue, and we are committed to maximising the opportunities to support new markets that use significant and reliable volumes of priority materials,” Mr Krpan said.

“It’s also an opportunity for universities and industry to work together to develop practical solutions to an important, and costly, community issue, which will benefit us all.

For more information about applying for the grant, click here.

Lomwest build wall of used tyres in WA

Tyre Stewardship Australia (TSA) accredited recycler, Lomwest Enterprises of Western Australia, has created a high-performance wall system made from baled used tyres contained within concrete skins.

These walls can be used as retaining walls, sound barriers, sea and blast walls, cyclone shelters and race track impact barriers.

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TSA said in a statement that the modules for the flexible use wall system (called C4M) are manufactured offsite, allowing quick, easy and safe onsite construction. They can also have their outer surfaces architecturally modified to fit in with or enhance their environment.

Each C4M module contains 100 tightly baled used car tyres, sandwiched between precast panels and can be up to 2.4 metres in height. They also meet Australian and New Zealand stability, durability and relevant load standards, including for cyclone shelter construction and as fire rated partition walls.

Lomwest is just one of the many TSA accredited recyclers focused on developing, commercialising and promoting new uses for old tyres. The common feature of such new product development is a focus on creating better solutions for existing needs.

The TSA Market Development Fund is supporting a Curtin University independent assessment of the C4M walls. The objective being to fully quantify the benefits of the innovative wall system in a wide range of applications and therefore to expand the opportunities for beneficial use of end-of-life tyres.

“We are very pleased to be working with Lomwest and Curtin University on this exciting research,” said TSA Market Development Manager, Liam O’Keefe. “Developing the market for end-of-life tyres requires multiple outlets providing for a diverse range of applications. That includes a balance of refined-process powder and crumb using products and high-volume, low-process applications such as the C4M wall system.”

Glass and plastics could be used to help build footpaths

End-of-life plastics and glass fines could soon be used in the construction of footpaths instead of going to landfill, according to a new study from the Swinburne University of Technology.

The research found plastics and glass fines could be incorporated into concrete footpaths while still meeting the standard requirements, and without compromising the mechanical properties.

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It is estimated that approximately 100,000 tonnes of flexible plastics end up in landfill each year, and only 48 per cent of glass waste is recovered for recycling, according to Sustainability Victoria.

The next step for this project is to include local governments and industries to increase the amount of recycled content in footpath construction.

“The use of recovered plastics and glass fines in concrete footpaths will divert significant quantities of these materials from landfill, while reducing the demand for virgin construction materials,” said Swinburne University of Technology’s Dr Yat Choy Wong.

This research project is one of seven projects that investigate new ways to increase the use of recovered class and flexible plastics.