Cooler tarmac to cut CO2 and costs

Roadbuilders in the UK could save £46 million and prevent 260,000 tonnes of CO2 emissions by using cooler asphalt mixes, according to the Carbon Trust and Lafarge

A three-year industry study has revealed that switching to lower temperature asphalt (LTA) when laying new roads can reduce carbon emissions by up to 39%.

Conventional, “hot mix” asphalts, heat bitumen and aggregates to 180°C–190°C to bond them together, while LTA mixes are only heated to between 70°C–140°C.

The project, which was part funded by Decc and led by the Carbon Trust and Lafarge Tarmac, trialled the use of an LTA mix and confirmed it was as effective as traditional hot mixes.

The energy saved as result of working at lower temperatures significantly cuts cost and carbon emissions, confirms the study. The Carbon Trust estimates that if just 21% of the asphalt laid in the UK over the next 10 years was produced at the lower temperatures it would save £46.2 million and around 260,000 tonnes of CO2.

As a part of the project, the Transport Research Laboratory has published a series of example procurement specifications for LTA, as current existing national and European standards are based on hot mixes.

“This pioneering project will fundamentally change the asphalt industry in the UK to produce sustainable low-carbon products,” said Nizar Ghazireh, project director at Lafarge Tarmac. “The specifications will assist clients to procure these materials as standard products and feedback from their use will inform the future development of the European standards.”

Doug Sinclair, office director of the Highways Agency’s major projects portfolio, said: “Carbon reduction is all about innovation – you only get different results by doing things differently – it’s that simple.”

Currently the UK’s asphalt sector produces around 786,000 tonnes of CO2 each year. Last September, the West Midlands Highway Alliance committed to cutting carbon emissions from manufacturing materials for roads and footways by 20% by 2015. Keith Gordon, assistant director of efficiency and delivery, confirmed that the body was on track to lay more than 300,000 tonnes of LTA in 2014.

The Transport Research Laboratory’s specification for LTA can be downloaded free from: trl.co.uk