Use of recycling elastomers - a contribution to increasing sustainability in asphalt road construction?

Abstract

When designing a construction method and selecting the individual construction materials, the topics of sustainability, climate protection and resource conservation are becoming increasingly important in asphalt road construction. The current situation in road construction, i.e. increasing raw material prices and simultaneously decreasing availability of primary construction materials, will increase the importance of the re-use of secondary construction materials. Rubber-modified asphalts have been used successfully for many years as an alternative to polymer-modified asphalts. Rubber-modified bitumens consist of a road bitumen modified with additivated rubber powder (secondary construction material from recycled tires). However, the good practical experience to date has only been partially documented, if at all, by verified data. On the basis of three long-term studies on the mode of action and performance of the rubber-modified construction method with considered periods of use between 10 and 13 years, a highly loaded industrial area (2007), a logistics and container area (2008) and a city road (2012) were examined and evaluated by the engineering company PTM Dortmund mbH. In addition, investigations (performance and emissions) and dimensioning calculations com-paring polymer-modified to rubber-modified construction methods were carried out as part of a pilot route (2020). The previous positive experience with the rubber-modified asphalt construction method was con-firmed by long-term observations and comparative laboratory tests. The highly loaded asphalt surfaces inves-tigated still show good performance properties even after comparatively long service lives. With regard to the calculated service lives, it was also possible to derive equivalent or even higher service lives for rubber-modified asphalt variants compared with the classic polymer modification. In summary, the results show that the rubber-modified asphalt construction method can make an additional contribution to the main sustainabil-ity goals, such as resource conservation, the reduction of CO2 emissions or the reduction of life cycle costs through the extension of service lives.