Effects of Reclaimed Asphalt Pavement on Mechanical Characteristics of Asphaltic Mixtures for Surface Layer

Abstract

Reclaimed asphalt pavement (RAP) is considered one of the valuable alternatives to raw materials due to reducing the need to use raw materials, which are less in some world regions. It additionally reduces the highly-priced new bitumen required inside the asphaltic mixture manufacturing and contributes to the preservation of natural resources. To achieve maximum benefit from the integration RAP in asphaltic mixture, it is necessary to investigate the advantages and disadvantages of the recycling process on the properties of asphalt pavement. This study examines the effect of adding reclaimed asphalt pavement by different percentages on the mechanical properties of asphaltic mixture for the surface layer in terms of Marshall's stability, Retained Marshall stability, indirect tensile strength, and compressive strength. Two types of asphalt grade (40-50) and (60-70) were used in addition to one type of aggregate gradation of the wearing course to prepare the asphaltic mixture. The Superpave system was applied to select the best aggregate gradation and optimum asphalt content using Superpave Gyratory Compactor (SGC) and to prepare compacted asphaltic specimens of 100 mm diameter for simulating Marshall’s molds. PAP is added by four different percentages of (7, 13, 19, and 25) % by the weight of the total asphalt mixture, and samples are prepared to compare the mechanical properties with conditional ones. The results show that adding RAP to the asphalt mixture improved the measured properties. In contrast, the mix containing RAP showed lower loss of stability, lower loss in indirect tensile strength, higher stripping resistance, and better durability than the mixture without RAP.