Usage of Reclaimed Asphalt Material in Stone Mastic Asphalt

Abstract

The paper focuses on the issue of using reclaimed asphalt (RA) in asphalt mixtures used for highly traffic-loaded asphalt pavements—in asphalt mixtures of the stone mastic asphalt (SMA) type. It is a skeleton-type mixture, where the traffic load is bore by a skeleton of coarse aggregates bonded with mastic (i.e., bitumen and fine aggregates). It is therefore essential to pay close attention to the properties of this coarse aggregate. Higher demands on properties of the aggregate are probably due to the fact that RA is not currently being used in SMA-type mixtures. Most standards do not allow usage of RA in this type of mixtures. Given that traffic load of road networks is constantly increasing, the ratio of SMA-type asphalt mixtures also increases in the road network. This paper presents results of 5-year research focused on the possibility of using RA in SMA-type asphalt mixtures. This included laboratory design of these mixtures with various dosages and types of RA. Their empirical and functional properties were verified. Based on the positive results of the laboratory testing, a test section was subsequently constructed using several variants of the mixtures containing up to 50% of RA. This test section is regularly being monitored, and despite very intense traffic load, there are no failures apparent after 2 and half years of operation. Based on the laboratory research and subsequent construction and monitoring of a test section, it can be said that RA can be used in SMA-type mixtures without any negative impacts on functional properties or mixture lifetime.