With concerns for the countryside high on the agenda, pressure is growing on the Construction Industry to green up its act when sourcing aggregates. Michelle Barratt investigates the issues that could pose a potential planning headache for aggregates firms.

Nearly 300m tonnes of aggregates are used in the UK each year, and if demand increases by an expected 1% per annum, the country will need an extra 20m tonnes by 2012. Contractors are urged to use more recycled demolition and construction materials such as concrete, bricks and tiles, and secondary source industrial by-products such as colliery spoil, china clay waste, slate and power station ash.

Historically these have been used as low quality fill due to their lack of consistency, as Miles Watkins, group environment manager for Aggregate Industries tells B&E.  “There are technical barriers relating to the consistency of the material,” he says. “If you can get consistent material, you can usually carry out relatively well-performing tasks with it. The problem is if you are using a basic construction and demolition waste, then it is normally very badly sorted. You can either spend lots of time and money sorting it or you can only ever use it in a low performance application like a fill.”

Watkins says secondary aggregates are much more consistent. “Crushed glass and waste from china clay or incinerator ash is much easier to deal with, especially if you are trying to use it in value-added products like asphalt and concrete materials.”  To promote the use of sustainable aggregates, the Waste and Resources Action Programme (WRAP) developed a dedicated Aggregates Programme. Despite its attempts to break down the barriers, there is still some way to go, as John Barritt, the organisation’s aggregates technical advisor explains.

“Initially there was a perception of risk that recycled materials might not be as good as primary materials,” he says.  "Specifications didn’t permit people to be able to use the materials on a lot of the work. There was also a lack of availability of higher value, quality recycled materials.”

Wrap has produced information on its Aggregain website to demonstrate these specifications and the type of materials that comply with them. “We have over 150 case studies showing where they’re being used, who’s used them and what applications they’ve gone into,” says Barritt. “We also have a list of contractors so that people can see reputable contractors are using them in high quality applications supplied by reputable suppliers.”

One such project was the widening of the M25 at Heathrow Terminal 5 where Balfour Beatty used 800,000 tonnes of recycled aggregates. “Some people say it might not be good enough for their own little road,” says Barritt, “but I think if the M25 uses it then most people shouldn’t really have a problem.”

Barritt says contractors are using recycled and secondary aggregates in a much wider range of applications. "Technically, crushed concrete is allowed to the British standard for concrete. This is very high strength concrete so it’s just a matter of availability in terms of location and quantity relative to different applications.”

But is using recycled or secondary aggregates always the more environmentally friendly option?  Although Wrap was formed to stimulate the market for recycled materials, Watkins is hesitant to promote the products in every project.“On the strict substitution of a new product with a second-hand one, then yes, I would agree that it is more environmentally-friendly,” he says. “But the haulage distances and the energy required to sort and process these secondary and recycled aggregates sometimes means that they’re not actually that beneficial, if at all.”

Indeed the environmental impact of construction covers a wide range of issues and assessing such different issues in combination requires subjective judgments about their relative importance. To enable such assessments to be made, the Building Research Establishment (BRE) has developed the Ecopoints system. An Ecopoint score is a measure of the overall environmental impact of a particular product or process. The higher the Ecopoints score, the greater the environmental impact.

Watkins backs the project as a good kick-start for the recycled aggregates industry. “The BRE Ecopoint rating scheme is the backbone of a lot of things that are going on at the moment,” he says, “particularly the Code for Sustainable Homes, which will be launched at the beginning of next year. Anything you can do to reduce waste is going to help the developer score more points.”

But long-term, designing buildings so they can be properly decommissioned is going to be much more effective, Watkins says. “What typically happens when buildings are demolished is that you end up with a big pile of rubble, which isn’t very clever if you’re trying to reuse and recycle bits of it,” he says. “Designing in a manner where a building can be taken apart into its constituent bits, and then reused, makes much more sense.”

Wrap feels demolition is such an important issue that the Aggregain website has devoted a whole section to the subject. “Demolition on the Aggregain website has various templates for assessing a building that’s going to come down,” says Barrit. “It is also looking at new builds and producing a schedule of what materials can come out, how they’re going to be used, what materials are needed and how you can integrate materials that are coming out of deconstruction into new  cnstruction.”

Steps are being made in the right direction to promote recycled aggregates and both Barritt and Watkins agree that cnstruction needs to be looked at in a more sustainable way. Barritt says: “To get people to do that, ou have to get them to look at things from a broader perspective, not just the material they use but the way in which they use it.”

The increasing stress we put on resources and environmental systems cannot go on forever. We need to make a decisive move toward more sustainable development. Not just because it is the right thing to do, but also because it is in our own long-term best interests. By reducing the emphasis of extracting primary aggregates from the ground, recycled agregates are helping the construction industry to become more sustainable – in other words, not using up assets today that our children may need tomorrow. The small everyday actions will add up to make a big difference.