Investigation of Working Binder in Hot-Mix Asphalt Containing Recycled Asphalt Pavements

This study investigates the effect of the amount of reclaimed asphalt pavement (RAP) on the volumetric and mechanical properties of hot-mix-asphalt (HMA). To better understand the effect of the RAP binder on HMA, six different job mix formulae (JMF) containing 0, 20, and 40% RAP from two sources were prepared and tested for complex modulus and moisture susceptibility. The optimum asphalt of the JMFs did not change between virgin HMA and the HMA containing RAP. The selective absorption effect on virgin materials compared to RAP materials was manifested in the complex modulus results. However, the complex modulus results indicated that aggregate structure due to the use of RAP makes it difficult to accurately determine the amount of working binder. The study also concluded that these RAP materials may potentially improved the moisture susceptibility of the mixes. In addition, the indirect tensile strength of the mixes at room temperature increased when RAP is included in the mix.