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Ammann continues to reduce carbon dioxide emissions
18. December 2009

Low-temperature asphalt and asphalt recycling reduce carbon footprint.

The concentration of C02 in the atmosphere rose from 320 to 386 ppm (parts per million) between 1958 and 2000. As a result, the global temperature has risen by 0.7°C and the sea level by 17 cm. The snow-covered regions of the Earth have been reduced by 10%. Modern technology can help to significantly reduce the carbon monoxide emissions of a standard asphalt plant and save costs to boot. Ammann is at the forefront of these groundbreaking developments. Model calculations on the future of the global climate are based on various scenarios: one of the more optimistic assumes an average warming rate of 1.8°C by the year 2100. As a reaction to these insights, the countries that have ratified the Kyoto Protocol have agreed to reduce the levels of CO2 and other greenhouse gases to 5% below the value of 1990 – a goal it is hoped will be achieved between 2008 and 2012. Every sector of industry and every member of society is called upon to contribute towards achieving this globally agreed goal. The asphalt mixing plants used in asphalt road construction are a major source of CO2 emissions (see box), as the majority of energy is used to dry and heat the aggregate. This energy stems from fossil fuels. Ammann has a number of solutions at its disposal that will contribute towards achieving the global goals relating to CO2 reduction. The two decisive aspects of a ”greener” asphalt industry are lower operating temperatures and the use of as much recycled asphalt as possible. In general, the following rule of thumb applies: ”Energy consumption equals CO2 emissions, and energy consumption also equals production costs.” This means that a reduction in energy consumption goes hand in hand with a reduction in production costs and CO2 emissions.

 

Fewer emissions with low-temperature asphalt

Lower asphalt mixing temperatures lead to reductions in many kinds of emissions. That is why the industry is introducing a so-called warm-mix asphalt. This asphalt is produced and processed at a temperature of around 100°C instead of the usual 160°C. The advantages of low production temperatures are obvious: less fuel consumption and speedier cooling mean traffic can flow again sooner. Additionally, emissions (gases and smoke) are also reduced on the plant and on the building site, resulting in a significant improvement for workers, machine operators and neighbours. Various methods of producing low-temperature asphalt are available; they include, for instance, the use of additives, foams, special types of bitumen or a combination of these methods. It is usually possible to lower the mixing temperature by at least 20°C and sometimes by as much as 70°C. Various technologies are available on the market depending on the plant operator and the conditions on the construction site. Ammann offers a range of solutions for producing low-temperature asphalt, such as additive feed or the use of WAM foam technology (see box). The solutions range from special modules in the plant control system to additional plant components.

 

Asphalt recycling through parallel drum technology

According to studies, the production of new bitumen causes 13 kg of indirect CO2 emissions per tonne of new asphalt. Increasing the proportion of recycled asphalt is therefore equivalent to a direct reduction in overall CO2 emissions of the road construction industry. Even today, large quantities of asphalt are simply placed into storage or used for insignificant applications. However, it would be more appropriate with regard to sparing our resources to use the available recycled asphalt gained from high-quality bitumen and processed aggregate in high-performance plants for the construction of new, long-lasting roads. Ammann recognised the importance of asphalt recycling at an early stage. Ammann introduced parallel drum technology more than 20 years ago; it has meanwhile become the recognised standard for quality recycled asphalt. Ammann continued its innovative course in 2008 by introducing the first drum with counterflow technology that enables the asphalt industry to utilise 100% of recycled asphalt (see box). The route to greener roads is therefore predetermined.