Evaluation of Using Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt of Pavement layers

Abstract

Recycling the old paving waste and reusing it in the construction of new highways is a good step from an economic point of view, as well as from an environmental and health point of view, morover producing more sustainable asphalt mixtures, as it reduces carbon emissions and eliminates the large amount of disposable reclaimed asphalt pavement materials (RAP). The aim of this study is to evaluate the best layer of pavement structure; base, binder, and surface layers for inclusion (RAP) materials. In addition, highlight the best percentage that can be added from RAP to achieve positive results and better than that associated reference mixture in terms of Marshall test, Indirect tensile strength test, and deformation resistance RAP materials collected from different sources Karbala and Fallujah, were adopted in this study at percentages of 20%, 30%, and 40% by weight of the asphalt mixture. Two scenarios of incorporating RAP materials have been adopted. The first is considered that RAP as a black rock in which the effect of aged binder surrounding the aggregate of RAP is neglected while, the letter is not considered RAP as black rock and the influence of aged binder in RAP materials has been taken into consideration. Moreover, the study has addressed the effect of source bitumen in which, two sources of bitumen were used Dora and Nasiriyah bitumen’s, which are used in common in Iraq. It has been found the best layer in which RAP can be incorporated is the base layer, with a percentage up to 40% that RAP without considering RAP black rocks regardless the sources of bitumen and RAP in terms of deformation resistance test. In terms of stability, it was found that there is an improvement in the stability values in case of adding RAP of Karbala with Dora bitumen without considering RAP as black rock regardless of IV layer type compared to that of reference mixture. With reference to the indirect tensile strength test, it was revealed all asphalt mixtures containing RAP materials had higher values than that of the reference mixtures taking into consideration RAP should not be considered black rocks regardless of sources of bitumen asphalt mixture of layer type. According to what has been found in the current research, highway agencies in Iraq are highly recommended to take the advantages of inclusion RAP materials in the pavement structure.