Greener blacktop
14 Feb 2003
Shell claims that its 'WAM-Foam' enables asphalt - commonly used for surfacing roads and pavements - to be produced at lower temperatures, providing savings on fuel costs and reducing greenhouse gas emissions.
Developed by Shell and the leading Norwegian asphalt manufacturer Kolo Veidekke, WAM-Foam (warm asphalt mix) typically reduces energy consumption and carbon dioxide emissions by a third. If adopted by just 1% of the world's asphalt producers, Shell claims it could reduce the industry's carbon dioxide emissions by 72 kt a year.
NCC, the largest asphalt producer in the Nordic countries, has already implemented the technology and America's National Asphalt Paving Association has asked Shell Bitumen and Kolo Veidekke to present it at their annual meeting.
Traditionally, manufacturers have used a 'hot mix' technique that required heating the asphalt mixture for road making to 150-180 degrees C so that the bitumen can fully coat the dried aggregates (stones and sand). This ensures that the asphalt mixture is fluid enough to be workable during mixing, laying and compacting, processes that take place at 130-160 degrees C.
With WAM-Foam, the mixture needs to be heated to only 100-120 degrees C and can be compacted at around 80-90 degrees C which also reduces the fumes produced.
According to Shell, road and laboratory tests show that roads and pavements produced using WAM-Foam are as durable as those made with hot mix technology.
