Performance evaluation of microsurfacing mixture containing reclaimed asphalt pavement

Abstract

ABSTRACT Environmental issues of reclaimed asphalt pavement (RAP) production and efforts to preserve natural mines are among the main factors for the use of RAP. Besides, the characteristics of RAP can improve some properties of asphalt mixtures. Since these materials are produced during the maintenance or rehabilitation process, they are better to be consumed in the same procedure. One of the best methods for pavement maintenance is the use of microsurfacing as a surface treatment. In this regard, the use of RAP in the microsurfacing mixture further enhances the application of this method. In the present study, first, the feasibility of using almost 100% RAP instead of virgin aggregate (VA) was studied according to the microsurfacing mix design tests. Then, 69% and 43% RAP contents were also evaluated to determine the preferable RAP content and better analyze the results. The results showed that the design of microsurfacing mixture containing RAP met the criteria of the international slurry surfacing association (ISSA) guideline. RAP-containing mixtures needed about 1% more bitumen than those containing VA to obtain sufficient cohesion within the specified time. Nevertheless, mixtures containing more RAP content would require lower amounts of additive to increase the mixing time and workability, which could reduce the cost of material preparation. The adhesion of bitumen emulsion with the aged bitumen spread over the RAP aggregate surface was less than its adhesion to the VA and was aggravated in a wet environment. RAP-containing mixtures displayed a more appropriate behaviour in association with the flushing distress. Also, RAP aggregate coating prevented the stripping of these materials in the vicinity of water. Among the RAP-containing mixtures, the one with 69% RAP outperformed the other ones.