Hanson's Reduced-emission Asphalt

First published in the January 2021 issue of Quarry Management as A Breath of Fresh Air

Hanson’s reduced-emission asphalt (REA) paves the way for cleaner air 

Air quality is an issue which impacts countries across the globe, particularly in cities, where poor air quality can result in both short-term and long-term effects on people’s health.

To minimize the impact on air quality when producing and laying asphalt – and not exacerbate air quality issues – Hanson are offering their customers a range of reduced-emission asphalt (REA) products.

REA has been developed using Shell Bitumen FreshAir, a specialist binder which actively reduces specific gases and particulates emitted during asphalt production and laying by an average of 40%, compared with conventional bitumen. REA also reduces odour for neighbours and construction workers, improving working conditions.

Shell Bitumen FreshAir consists of active inhibiting components which act directly with selective compounds that are the source of gases, particulates and odour-releasing molecules. The chemical reaction occurs in situ at molecular level, which helps to reduce gases and particulates or minimize their ability to become airborne, thereby reducing the impact on air quality.

Shell’s global research and development team conducted an extensive laboratory study, covering thousands of different tests on an extensive range of bitumens, to investigate the impact of Shell Bitumen FreshAir on different air quality indicators, as well as any potential impact in bitumen properties and asphalt mixture performance.

These in-house laboratory findings were validated through an extensive series of externally monitored field trials in Thailand, France, the Netherlands and the UK. Over the last two years, the technology has been commercialized and used in France, Germany, Hong Kong, Singapore, The Philippines and China.

‘REA demonstrates that there is a cleaner way of producing and laying asphalt, enhancing the environmental image of the material,’ said Gareth Day, Hanson UK asphalt managing director.

‘It is particularly beneficial for cities, ultra-low emission zones and other areas with compromised air quality, minimizing the risk of exceeding short-term air quality levels during construction works.

‘Its use can improve air quality during the road-building phase – particularly in tunnels, where ventilation is an issue, and urban areas – as well as during production.

‘REA is also affordable and can be used in all Hanson asphalt products for a wide range of applications, making it easy to switch to specifying REA to reduce the risk of exceeding air quality levels during production and laying.’

In addition to its air quality benefits, REA does not affect the engineering properties of the bitumen or asphalt – ensuring quality, skid resistance and durability.

Every kilometre switched to REA is estimated to have a similar effect on particulate matter (PM10) as planting 16 trees and a similar impact on the reduction of NOx as removing 40 cars from the road.

The new products can also be used in conjunction with Hanson’s energy-reducing asphalt (ERA), the company’s warm-mix technology, allowing the air quality benefits to be combined with lower CO2 emissions. Using the ERA production process typically saves 2.4kg of CO2 emissions per tonne of asphalt laid. 

Case study: A sustainable solution for Tesco 

REA has been specified for Tesco car parks in Tadcaster (North Yorkshire), Whitchurch (Shropshire), Longton (Stoke-on-Trent) and St Helens (Merseyside), to help meet the retailer’s sustainability targets and its key innovation and value drivers. More than 3,100 tonnes have been laid by NMC Surfacing across the four sites, with more planned.

The combination of Hanson’s ERA warm-mix asphalt technology and REA provides a sustainable solution: using ERA realised a saving of 7,630kg of CO2 emissions, compared with conventional hot-rolled asphalt, while the REA used is estimated to have a similar effect on particulate matter as planting 146 trees and a similar impact on the reduction of NOx as removing 366 cars from the road.

‘Tesco were looking for an innovative new surfacing solution to meet their sustainability targets and those of their stakeholders,’ said Haroon Rashid, managing director of NMC Surfacing.

‘Hanson REA combined with their ERA technology ticked this box as well as the retailer’s key drivers of innovation and value.

‘We have been very impressed with the quality and performance of the material and Tesco have plans to use it to resurface more of their car parks over the coming months.’

Hanson REA – the benefits:

• Average 40% reduction of specific gases and particulate matter
• Reduced impact on air quality during production, paving and compaction of road surface
• Substantial impact on NOx, SOx, CO, VOC and PMs
• Similar effect on NOx as taking 40 cars off the road per km asphalt laid
• Equivalent effect on particulate matter as planting 16 trees per km asphalt laid
• Active odour neutralization of 95–99%
• Perfect solution for Ultra Low Emission Zones (ULEZs)
• Can be used in any asphalt product range
• Suitable for all asphalt applications.

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