Total Bitumen is championing lower temperature asphalt by providing customers with enhanced binders that reduce mixing temperatures by around 40°C.
Binder produced in the UK containing special additives is now being offered by Total Bitumen to allow asphalt suppliers to mix lower temperature materials without having to invest in new production equipment. The company’s new ‘Azalt Eco²’ binder range was launched in the UK this year and typically allows for a 40°C drop in asphalt mixing temperatures. Tests in France show that the final product offers comparable performance to standard hot mix materials.
“Our main selling point is that the binder is supplied with additives already incorporated. This means that producers can mix lower temperature asphalt without having to make a capital investment in modifying their plants,” says Total Bitumen’s UK Market Development Manager Rick Ashton. “There is no need to inject water into the mix to foam the bitumen or modify it in other ways during production; it comes ready to use in the conventional mixing process but at lower temperatures.”
Offering an enhanced binder to producers of warm mix asphalt could help customers to save over £250,000 by not having to fit new hardware to their plants, Mr Ashton adds.
Two trials carried out by Total Bitumen in France during the last couple of years have demonstrated the binder’s favourable performance in warm mix applications. Azalt Eco² was developed at Total’s research centre in Lyon as part of the Total Group’s Ecosolutions programme, which is independently audited by Ernst & Young. The first trial site at Blois in central France made use of 500t of Azalt Eco² for a new surface course on a heavily trafficked route.
Asphalt was manufactured at 120°C against a control section of hot mix, the plant’s baghouse filter was monitored for efficiency and no blocking was experienced. Energy consumed by the burner at the asphalt mixing plant was found to be 35% less with the warm mix compared to hot mix. Overall emissions were 47% lower during manufacture – which helps to reduce airborne odour – and carbon dioxide emissions were down by 30%.
“An extensive laboratory analysis of the mixes revealed that the performance of the warm mix material was as good if not better than standard hot mix,” Mr Ashton says.
Material featuring Azalt Eco² was applied to the road at Blois at 115°C and compacted at around 110°C, around 40°C cooler than conventional hot mix material. After one year in situ an inspection revealed no visual differences between the Azalt Eco² and the control hot mix section with no deterioration in ride quality. Transverse deformation measurements were found to be small and variations in macro texture were slight, confirming that the material had performed well. No differences in ride quality were reported, Mr Ashton adds.
The second trial site at Rennes in Brittany looked to provide further validation of the material’s performance and was laid on an access road and parking area used by heavy goods vehicles. Careful consideration was given as to whether the binder gave a good coating of the aggregate and to see if the mix could be compacted well at a reduced temperature.
Warm mix asphalt was mixed at a temperature of 125°C, applied to both surface and base courses at 120°C and compacted at around 100°C. The surface course made use of 10mm aggregate, the binder 14mm aggregate. Recycled asphalt pavement (RAP) was included in the material to improve its sustainable credentials; with the surface containing 10% RAP and the base 20%.
“Azalt Eco² potentially allows for higher percentages of RAP addition as binder oxidation is reduced during mixing in comparison to hot mixing,” says Rick Ashton. “This offers manufacturers further economic and environmental benefits.”
Energy consumption at the mixing plant reduced by 20% and visual observations of the road after 18 months found no signs of deterioration. “Compaction was actually slightly better on the warm mix compared to the hot mix control section,” Mr Ashton adds.
Since the two trials were completed around 20,000t of asphalt containing the Azalt Eco² binder has been applied at a series of sites across France from Bitche in the North East to Bordeaux in the South West. “In France the product has gone beyond trial stage and is recognised as a commercially viable material,” Mr Ashton adds.
“Operatives report that they like using our warm mix material because it looks like a conventional hot mix asphalt, rather than being brown or grey in colour.”
Total Bitumen’s National Sales & Marketing Manager John Tuite says: “There is a market interest in lower temperature ready to use bitumens that do not require any plant modification or investment.” Mr Tuite adds that “strong technical relationships within Total Bitumen’s expanding worldwide activities – such as with our French colleagues – enable us to transfer technologies from one country to another. As a result Azalt Ec² trials have now started in the UK.”
Mr Ashton adds: “Selecting warm mix over conventional hot mix asphalt has the advantage of reducing fuel costs and cutting carbon emissions during manufacture. And starting with a cooler material on site means that the road can be reopened to traffic sooner.”
He adds that customers can now produce warm mix asphalt without specialist knowledge, plant modifications or the need to pay ongoing royalties. “This is Total’s technology and our lower temperature ready to use bitumen applications will continue to evolve in the asphalt market.”
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