Asphalt recycling and foam bitumen – a combined approach

Abstract

To save resources and reduce the energy consumption during asphalt mix production there are three main approaches: addition of reclaimed asphalt (RAP), lower production temperatures, and reduced moisture content in raw materials. Whereas a high moisture content only influences, thus increases the energy consumption and emissions in the plant, RAP addition and lower production temperatures have a direct impact on asphalt mix properties. The main goal of this study is the production of high quality asphalt mix. Experience has proven that high ratios of reclaimed asphalt can be incorporated into hot mix asphalt at equal quality. Furthermore using foam bitumen to produce warm mix allows mixing and compaction at reduced temperatures with comparable properties to hot mix. Combining asphalt recycling and foam bitumen is a step forward to an efficient and sustainable use of resources. The feasibility of producing high quality warm mix asphalt with foam bitumen and various high RAP percentages was demonstrated in field trials. In several asphalt mixing plants mixes were produced, paved and compacted at reduced temperatures. Asphalt production and laying was attended and analyzed. Additionally, for direct comparison construction sites with conventional hot mix were observed. Mechanical mix properties equal to hot mix asphalt were found independent of the RAP content and production temperature.