Australia’s annual construction activity is valued at about $230 billion, and this economic headline provides one indication of the scale of works being undertaken around the nation. Another indicator is the 19 million tonnes of annual waste by-product associated with construction and demolition (C&D) activities.
The C&D sector is responsible for about 40 per cent of all Australian waste material, with the commercial and industrial sector accounting for 30 per cent and the household municipal sector another 30 per cent.
While there is a lot of waste by-product associated with construction activity, the National Construction and Demolition Waste Status Report published by the Australian Government in 2011 shows a large portion of this material – about 55 per cent – is already being recovered and recycled. In some states, recycling rates of more than 75 per cent are being achieved.
In November 2009 Australia’s environment ministers, through the Environment Protection and Heritage Council, released the publication National waste policy: Less waste, more resources. It sets out a comprehensive agenda for national co-ordinated action on waste, and marks a fundamental shift in the approach to waste management and resource recovery.
As the title suggests, a key theme of the policy is developing markets and systems that mean by-products from one activity can be used as a resource to support another, instead of being treated as a “waste” product that needs to be disposed of. By reusing valuable materials, the aggregates industry can avoid the need to manufacture new materials from scratch, providing a host of social, environmental and economic benefits.
Modern recycling activities involve the use of high-tech equipment to process and prepare large volumes of materials. But while the industry has become much more organised and sophisticated over the past several decades, it is important to recognise that “recycling” is just a new term for a very old concept. Throughout the history of humankind, people have benefited from reusing valuable materials to avoid the need to buy or make a new product from scratch.
The term “sustainable aggregates” is used to describe products manufactured from recycled C&D materials. It is estimated that more than nine million tonnes of masonry by-products were recycled in Australia in 2008-09 and used to replace the need for virgin crushed rock in a wide range of applications.
There are several reasons these products may be considered more “sustainable” than virgin products:
- Products manufactured from recycled materials are considered more economical for customers, both in terms of cost per tonne and transport efficiencies.
- Using recycled materials can help to “close the loop” on resource use, avoiding the need to quarry more virgin materials and simultaneously reducing the amount of “waste” disposed to landfill.
As Australia grows, the demand for aggregate materials is much greater than could possibly be supplied using recycled products alone, and there will undoubtedly be a mixture of virgin and recycled products used, depending on the specific project and the relative availability of different materials.
Some potential customers for sustainable aggregates, however, are failing to take advantage of the benefits the products can deliver, because they incorrectly assume a “recycled” product cannot be as good as a “new” product. In some cases these perception issues create a barrier, even though major agencies such as state road authorities have undertaken long-term research and developed detailed specifications to encourage the use of sustainable aggregates in major projects.
Australia’s major sustainable aggregate producers adhere to the same stringent testing standards, and produce high quality materials that meet and exceed the same performance requirements demanded of their virgin rock counterparts.
Customers can be assured of the quality of sustainable aggregate materials by dealing with reputable business that can demonstrate their products meet the required specifications for the particular application and are tested at an independent, accredited laboratory.
When two products meet the same performance specification but one comes with a range of extra social, environmental and economic advantages, the smart decision for customers should be clear.
The Australian quarrying industry has estimated that the average consumption of aggregates across the country is about seven tonnes per person per annum, and has noted that demand “is likely to continue at present levels and will most probably grow in the future with the development of infrastructure”.
Of this 160 million tonne annual demand, sustainable aggregate products that contain recycled material currently supply less than 10 per cent. In most markets sustainable aggregates sell for slightly less than virgin products, even though they meet the same performance specifications and can offer an additional 10 to 15 per cent product volume, meaning users get more “bang for their buck”. It is important to realise that cheaper doesn’t mean lower quality; differences between the business models of recyclers and quarry operators can mean different production costs for the same quality end product.
The Inside Waste Industry Report 2011-12 estimated annual sales of sustainable aggregates totalled $160 million. However, many recyclers also charge a gate fee to accept demolition materials, which helps cover the cost of processing material to produce high quality products.
This is a significant difference from the business model in which it can cost a lot to quarry raw materials, even before processing them. The gate fees recyclers charge depend on the quality of incoming material, demand for finished products and local landfill disposal costs.
The economic rationale for sustainable aggregates is not just about the construction industry. Recycled steel extracted from crushed concrete offers a five per cent saving in steel energy costs as a percentage per tonne of output when compared with steel manufactured from raw materials. Some of the other economic advantages are brought to life through leadership in the industry, and the case studies in this publication showcase what is possible:
- ResourceCo has shown clean technologies can be introduced to traditional processing to create new revenue streams for the business from lighter waste fractions, also providing a new non-fossil fuel source for heavy industry.
- Alex Fraser Group has invested in state of the art processing facilities that can supply thousands of tonnes of high quality aggregates per day, to service demand for some of Australia’s highest profile construction projects.
- Capital Recycling is busting the myth that virgin materials outperform sustainable aggregates.
If all the surplus material generated during Australian C&D projects was treated as “waste”, it would keep at least 30 major landfill facilities operating all year round. Fortunately, a large portion of this material is being recovered and used to create valuable products, conserving airspace at landfills and avoiding the need to develop additional landfills in the future.
Clean masonry materials such as concrete, bricks and tiles are relatively simple to recycle and can be used to create a wide range of high quality products. Choosing products with recycled content not only helps keep this useful material from taking up limited landfill space, but it also means less need to quarry virgin rock.
While there is no physical shortage of rocks in Australia, a range of social and environmental issues can be associated with the quarrying of virgin materials. A life cycle analysis undertaken by RMIT University on Alex Fraser Group’s concrete recycling operations found that, across the full product life cycle, sustainable aggregates made from recycled concrete had a 65 per cent lower greenhouse emissions impact than similar products made from virgin rock. This was largely due to avoiding the energy needed to quarry rock, plus energy savings through recovery of reinforcing steel.
Customers, shareholders and communities also expect a bigger focus on sustainability by developers of major projects, and choosing sustainable aggregates can help to meet these expectations. The ABS Year Book Australia 2009-10 shows 82 per cent of Australians are “concerned” about the environment, and recycling is the number one activity they undertake within their own homes. Australians expect businesses to support recycling and efficient resource use.
Choosing sustainable aggregates means choosing the smarter option, extracting value from existing resources that would otherwise be wasted, while reducing the need to dig up more virgin rock. The more demand there is for products with recycled content, the more demand there is for recycling.
CASE STUDY: RESOURCECO
An inner city, seven-story building was demolished to make way for one of Adelaide’s largest city centre developments for more than a decade. This precision deconstruction process, undertaken by McMahon Services, generated more than 25,000 tonnes of materials, including heavy items such as concrete and steel, plus some lighter fractions such as wood and plastic.
ResourceCo is an integrated resource recovery business, operating processing facilities in South Australia and Victoria and manufacturing a wide range of recycled materials.
Heavy material from the Harris Scarfe demolition, predominantly concrete, was delivered to the company’s Wingfield site, where it was crushed into 10mm and 20mm aggregate products. Reinforcing steel from the concrete was recovered for recycling, where it displaces the need to mine virgin ore and provides energy savings in the manufacture of new steel products.
Through a joint venture with SUEZ Australia, ResourceCo has invested more than $20 million in a facility that can also recover value from lighter waste fractions that would otherwise be disposed to landfill. SUEZ-ResourceCo operates Australia’s first – and only – processed engineered fuel manufacturing plant, producing an alternative fuel with high calorific value, which reduces fossil fuel use at the Adelaide Brighton cement kiln.
Once deconstruction of the building was complete, McMahon Services undertook the early civil works package, which required more than 3500m3 of concrete to construct 665 building and retention piles forming the foundations of the Harris Scarfe redevelopment. This was sourced from ResourceCo Concrete, which maximises the use of sustainable aggregates in the manufacture of its concrete blends.
Depending on customer requirements, ResourceCo concrete can contain up to 45 per cent recycled content, with testing of all blends conducted by an independent NATA-registered laboratory to ensure it exceeds the same performance standards demanded of virgin concrete under Australian Standard AS 1379 Specification and Supply of Concrete.
Aggregates produced by recycling material from the demolition works were also reused during civil works to construct temporary piling platforms to allow the piling rigs to manoeuvre the site and construct the building and retention piles. Recycled aggregates were also used to construct the rubble platform beneath the new basement concrete slab.
- ResourceCo and ResourceCo Concrete are accredited with ISO 9001, 14001 and 18001.
- “Green” concrete meets the AS 1379 specification and design for normal class concrete.
- Testing carried out by an independent NATA registered laboratory.
CASE STUDY: ALEX FRASER GROUP
Alex Fraser Group has been in business for more than 130 years, and is Australia’s largest C&D recycler.
The company reached a major milestone in 2008, when it produced 20 million tonnes of recycled materials. To put that volume in perspective, if you were to fill the Melbourne Cricket Ground with this recycled material, it would form a tower 812 metres high.
A life cycle analysis conducted by RMIT University on Alex Fraser’s recycling processes found that producing aggregates from recycled concrete produces 65 per cent less greenhouse emissions than producing similar virgin quarried products.
Alex Fraser supplied aggregates for Peninsula Link from its Clayton site, one of Australia’s first C&D recycling facilities constructed in a fully enclosed shed to help reduce noise and dust issues. The Victorian Environmental Protection Agency described the site’s dust management technology as “beyond world’s best practice”, with sensors located throughout the site to deliver minute-by-minute information on dust levels.
The $23 million facility is just 50m from its closest neighbour, a high school. This proximity to residents drove the company to set a new standard in best practice design and operation.
Some 86,000 trees and shrubs planted around the site’s perimeter reduce its visual impact, while 95 per cent of water used at the site is recycled.
Peninsula Link is a 27km road that has seen an average trip between Mt Martha and Carrum Downs reduced to just 17 minutes – a saving of up to 40 minutes in peak periods. Abigroup chose Alex Fraser Group to supply sustainable aggregates for this project for several reasons:
- Location. Freight costs were very competitive because the Clayton facility was close to the construction site.
- Capability. The Clayton facility had the capacity to cope with the large volume required for the project.
- Quality. Alex Fraser had a track record in the supply of tested and specified Class 3 and 4 roadbase and aggregates to similar projects.
- Logistics. The ability to deliver up to 3000 tonnes per day (6000 truckloads of product required in total).
- Facility accredited with ISO 9001.
- VicRoads Standard Specification Section 820.
- Testing carried out by an independent NATA-registered laboratory.
CASE STUDY: CAPITAL RECYCLING
The City of Canning has entered a “double-ended” contract with Capital Recycling, which now accepts all the council’s C&D waste materials (more than 10,000m3 to date) and produces sustainable aggregate products from them. The council has so far purchased back more than 11,000 tonnes of product under the contract.
Welshpool Road is one of Perth’s major arterials, carrying about 8000 vehicles a day. About 15 per cent of these are trucks (including road trains), giving design traffic of about 20 million standard axles over a 30-year life.
In 2007 an 860m section of the road was upgraded, and the council took the opportunity to trial and monitor the performance of sustainable aggregate products.
Roadbase was manufactured from recycled demolition material, containing mainly concrete with some brick, tile and asphalt. The mix, which had a slightly lower maximum dry density than conventional roadbase (1.95t/m3 compared with 2.21t/m3) and higher optimum moisture content (11 per cent compared with six per cent), was easily worked and compacted well.
Different configurations were trialled, including one road section constructed with a recycled sub-base and conventional roadbase, another section using recycled material as a sub-base and base layer, and another section containing pure recycled concrete for the full pavement depth.
Several peer-reviewed papers report detailed results of the performance testing (available through Curtin University). Overall, sustainable aggregates performed equally, and in some cases better than, their virgin counterparts. The material was highly stable at a range of moisture contents, was easily worked and compacted, had better curvature characteristics and withstood the effects of turning traffic extremely well. The Welshpool trial gave the council confidence to now use sustainable aggregates in all its roadworks.
There is an abundance of accessible limestone in Perth, which means customers have access to relatively cheap aggregates. But the City of Canning recognises its community wants options to recycle their waste materials, and therefore the council must provide leadership in creating market demand for the products. There is no point in operators recycling materials if there is no market demand for them.
- Aggregates meet Main Roads WA Specification 501 – Pavements.
- Testing carried out by an independent NATA-registered laboratory
Reference and further reading
This article is based on the brochure Australia’s sustainable aggregates industry, published by the Commonwealth Department of Industry, Innovation, Science, Research and Tertiary Education, 2012. It is reprinted in Quarry with the kind permission of ResourceCo.
|Summary Products Table|
|SOURCE||PROCESSING MATERIAL||PRODUCT EXAMPLES|
|Concrete recovered during demolition works.||Large items of concrete are broken down to a size that can be fed into a crusher, with reinforcing steel recovered for recycling. A variety of fixed and mobile crushers are used across industry.||Recycled crushed concrete pavement material is used in the same circumstances as other crushed rock products. Principle use is in medium/heavily trafficked flexible base-course and sub-base.|
|Mixed builders’ rubble, mainly concrete, bricks and tiles.||Large items are broken down, with material such as metal and timber recovered for recycling before mixed masonry materials are fed into a crusher to produce blended aggregate products.||Aggregates in pavement sub-bases (such as roads), drainage, irrigation and landscaping applications.|
|Soil and sand from site preparation and excavation works.||May be screened to produce consistent size profile, depending on required product specification.||Certified virgin excavated natural material can be used as “clean fill”.|
|Rock and excavation stone recovered during civil or site preparation works.||This material may be identical to that produced at a commercial quarry, and will be processed using the same crushing and screening techniques.||Products generally bear no difference to aggregates made from virgin quarried materials.|
A breakdown of how secondary aggregate products can be recycled into premium end products.