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Posted: Oct 01, 2014
Demolish, re-use, recycle and rebuild
(Nanowerk News) Some 380 million tonnes of construction and demolition waste are generated every year and most of it ends up in landfills. Re-using and recycling components and materials is good for the environment and saves money, but industry has been less than enthusiastic. An EU-funded research project has laid the foundations for change - it is promoting concrete, ceramics, gypsum and plastics recycling around Europe.
Recycling and re-using parts from old buildings makes sense – it creates less waste, makes construction cheaper and reduces the use of raw resources (more than 50% of all materials extracted from the earth are currently transformed into construction materials and products).
The EU thinks it makes sense too, and in 2008 set a target: by 2020, the recovery of non-hazardous construction and demolition waste should rise to 70% – as measured by weight. But the industry has not followed suit.
There is a certain stigma attached to re-use, says Amaia Lisbona of Tecnalia in Spain, the company at the helm of the IRCOW project. “While it is trendy to re-use things in some sectors, like clothing, this is not the case in the construction sector, particularly in southern Europe,” she says.
Additional barriers are perceptions over quality (a component, whether it’s a door, window frame or sink etc., doesn’t come with tracking paperwork or certification) and unwillingness on the side of architects and contractors to take risks.
The IRCOW project prepared the ground for take-up with a study on these barriers, a demo online platform with stock exchange function, new recycling technologies and products and policy recommendations.
The project also carried out five case studies in Spain, Sweden, Poland and Belgium to test technologies, materials and processes in real-life conditions. In Bilbao, the IRCOW team took part in the selective demolition of a 1970s industrial building. “We were able to evaluate the impact of the demolition process (traditional or selective) and on-site recycling versus transportation to a fixed treatment plant,” says David Garcia, also of Tecnalia.
Stony material such as concrete and ceramics were collected, crushed and sieved on site, producing coarse and fine aggregates. These were then used to manufacture a range of concretes – one was used to create a slab that showed no signs of damage two years later.
Further indications of the concrete’s properties came when workers in Antwerp, Belgium, were asked to install IRCOW concrete. They didn’t notice a difference and were surprised to hear that the concrete was recycled.
It is fitting, then, that the Belgian region of Flanders, home to Antwerp, plans to become a European leader in the recycling of cellular concrete (thermally insulating concrete weighing in at just 20% of the weight of standard concrete) by 2020.
Manufacturing using recycled cellular concrete is at least 40% cheaper than using products made from raw materials. An agreement was signed at the final IRCOW conference between the demolition and construction sectors, plus all stakeholders in between. Flanders generates 50 000-100 000 tonnes of cellular concrete waste per year, of which 30 000 should be recycled in 2014 thanks to the agreement.
Second life for old gypsum plaster
Another of IRCOW’s successes is the manufacture of gypsum plasterboard (used for partitions, wall linings, ceilings, roofs and floors) from recycled gypsum. While other research groups have been investigating the recyclability of gypsum left over from manufacturing, the recycling of ‘dirty’ gypsum from construction and demolition waste was unique to IRCOW.
The result will contribute to guaranteeing closed material loops . Using an advanced sorting system and a near-infrared camera that recognises materials based on how light reflects off them, the team developed a way to identify and then extract gypsum from old plaster and other gypsum elements.
The sorted and recycled gypsum is dehydrated through heating before it is mixed with ordinary gypsum mineral to create new plasterboard. What makes the breakthrough even more exciting is that the gypsum can be recycled many times over.
The building sector has been particularly interested in concrete and gypsum recycling. Project partners are planning to market one of the recycled concrete mixes and technology manufacturing composites containing high levels of recycled construction and demolition waste materials (mineral wool, plastic, gypsum and wood) developed within IRCOW.
Meanwhile the IRCOW team has submitted a new funding proposal to continue this research, and in particular selective demolition and the technologies needed to recycle different types of waste.