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Recycled road surface ready to spread across the miles

36 recycled aggregate

Construction is the UK’s largest consumer of natural resources by a considerable margin. The UK Green Building Council estimates that the sector uses more than 400 million tonnes of material every year. It is also the largest producer of waste of any industry sector, responsible for around half of the 200 million tonnes of waste the UK generates annu­ally, according to Defra.

Highways and infrastructure is one of the more resource-intensive parts of the sector. The construction and maintenance of roads requires huge volumes of aggregates – the most quarried material in the world – and bitumen, a derivative of crude oil. Many of the materials used are recyclable but the industry still remains overly dependent on virgin resources.

There is significant investment planned for the UK’s road network in the coming years. Highways England, the Government-owned company that operates England’s motorways and major A roads, has committed £15.7bn to deliver more than 100 schemes between now and 2021, which will add around 1,300 lane miles to the network. With major motor-way development programmes in the pipeline, now is an ideal time for the industry to reassess how it sources and consumes construction materials and initiate the move towards a circular economy (CE).

Britain’s road network is estimated to be worth around £344bn. Part of this value lies in the commercial and social benefits our 187,000 miles of road brings to the country – but it is also in the billions of tonnes of asphalt, aggre­gates and other materials locked in the road network itself. Despite the fact that asphalt is 100% recyclable, the UK is poor at recovering and reusing road-building materials. Conservative esti­mates suggest there is up to two billion tonnes of asphalt in our roads that could be recycled yet we only recover a tiny proportion.

It is not unusual for highways teams to incor­porate up to 50% recycled content into the base and binder courses of a road – these are the two layers below the surface course. But for the surface course, the benefits of asphalt recycling remain largely underexploited. The roads industry remains wary of using asphalt with a recycled content of more than 10% for the top layer due to fears that high recycled con-tent mixes will not be able to offer safe levels of skid resistance.

These fears are not grounded in any proven limitations of the material itself – rather they are the result of ingrained industry custom and deep-rooted misconceptions about the proper­ties of recycled materials. If the highways industry is going to release the value currently locked in our roads, it needs to start thinking differently.

FM Conway has recently launched a trial with Transport for London (TfL) designed to prove that the use of high levels of recycled content in asphalt mixes for strategic roads is both safe and cost-effective, and dispel some of the myths that have arisen around road building and recycling.

The trial is taking place on the A1 at Mill Hill, north of London, where a surface course con­taining 50% recycled aggregate is being laid across two lanes. This will be monitored in the coming months, with its performance compared to conventional asphalt with around 10% recycled content to evaluate whether it retains the required surface texture and skid resistance.

The study will continue during the course of many months to allow the company to test road surface durability. It remains confident it can demonstrate that high recycled content asphalt meets all specified safety requirements and can therefore support the highways industry in its drive to be more resource efficient.

Highways England’s investment programme will likely see more than 50% of the strategic road network resurfaced by 2020-21. This offers a chance to recover a huge amount of asphalt for reuse, and provides a fantastic opportunity to ingrain recycling as part of the standard highways construction process.

By doing so, the sector will be able to mini­mise its carbon footprint and achieve signifi­cant cost savings by reducing the need to extract and transport virgin aggregates. This is particularly important in the south-east of Eng­land, where high-quality aggregates are scarce and must be imported, leading to additional logistics costs and carbon emissions.

Changing the culture and mindset of the highways industry to be more open to recycling is just one piece of the puzzle. There also needs to be the infrastructure – the recycling plants, vehicles and storage facilities – to make the recovery and reuse of large quantities of materials practical and affordable.

Bringing about a seismic shift in the ingrained culture of not just a business but a whole industry is not easy. It requires greater research and knowledge-sharing between stakeholders, as well as the time and money to establish the infrastructure to facilitate the change. There are, of course, environmental drivers for shifting to a CE but there is a clear financial impetus as well, and companies in all sectors need to think about how they can begin to make this change.

Ultimately, every industry is facing its own resource challenges. Policy-makers are placing increasing pressure on resource-intensive busi­nesses to make the transition to a CE. The trial currently underway with TfL should encourage others, both within and outside the highways industry, to reassess their long-held views about the benefits and limitations of materials recy­cling and move towards a circular approach to materials use.

£35M Investment Boosts Recycling

FM Conway has taken bold investment decisions in the past 10 years to allow it to become a materials supplier in its own right. This is part of the company’s strategy to deliver services itself wherever possible so that it does not have to rely on subcontractors and other parts of the supply chain.

asphalt manufacturing plants in heathrow

asphalt manufacturing plants in heathrow

It has invested £35m since 2010 to build asphalt manufacturing and recycling facilities that allow it to take materials recovered from its projects and use them to create new construction products. The asphalt manufacturing plants in Heathrow and Erith, Kent (pictured), are capable of producing more than 800,000 tonnes of asphalt a year using a high percentage of recycled materials.

The company says it has reduced the amount of virgin aggregates used in asphalt production by around 200,000 tonnes, and now recycles 98% of the waste generated by the projects it works on. The capital expenditure required to create such a recycling infrastructure represented a significant risk for FM Conway – but one which has paid dividends. It has significantly reduced its environmental impact. For the local authorities with which it works, this is an important performance indicator and has helped the company to win business.

By being in control of its own destiny when it comes to materials, it has also made our supply chain more secure and reduced costs.

Tim Metcalf is aggregates and asphalt director at FM Conway

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