Laboratory Investigation of the Effect of Using Reclaimed Asphalt Pavement on Micro surfacing Mixture Properties

Environmental issues of production of reclaimed asphalt pavement (RAP) and efforts to preserve natural mines are among the main factors for the use of RAP. Besides, the characteristics of RAP can improve some of the properties of asphalt mixtures. Since these materials are produced during the maintenance and rehabilitation projects, it is better to be consumed in the same operation. One of the best methods of pavement maintenance is the use of micro surfacing operation as a surface treatment. Therefore, the use of RAP in the micro surfacing mixture can enhance the application of this method. In this study, first, the feasibility of using almost 100% (95%) RAP instead of virgin aggregate, according to micro surfacing preliminary mix design tests was studied. Then, the values of 69% and 43% RAP content were also evaluated to determine the preferred RAP content and to better analysis of the results. The results showed successful preliminary design of micro surfacing mixture with RAP aggregate and met the criteria of the regulations.
RAP containing samples needed a little more bitumen than those containing virgin aggregates, to obtain sufficient cohesion within the specified time. Nevertheless, samples containing more RAP values would require lower amounts of additive to increase the mixing time and workability, which could reduce the cost of material preparation. Also, RAP aggregate coating prevented the stripping of these materials in the vicinity of water. Among the RAP containing samples, those containing 69% RAP exhibited a better performance.