A Performance review of warm mix asphalt containing reclaimed asphalt pavement materials

Abstract

The performance of warm mix asphalt (WMA) mixtures containing reclaimed asphalt pavement (RAP) materials has been studied extensively in both laboratory scale experiments and field experiments. Warm mix asphalt technology is using additives or water foaming mechanism to reduce the production and mixing temperatures of asphalt mixtures. At present, there are three main WMA technologies to produce asphalt mixtures: organic additives, chemical additives and foaming technology. The WMA technology is gaining popularity due to its economic and environmental benefits. The reduced temperatures allow WMA mixtures to incorporate high amount of RAP materials making the mixtures more economical. Nevertheless, incorporation of RAP has its own advantages and disadvantages. The performance of WMA mixtures containing RAP is one of the main concerns in the industry. Over the past decade, many studies have been conducted to investigate the performance of WMA mixtures containing RAP. However, many inconsistencies can be found in the literature regarding the performance characteristics of WMA containing RAP due to the availability of numerous warm mix asphalt technologies, inconsistency in RAP materials, use of various percentages of RAP, adhering to different testing methods to evaluate the performance etc. Hence, it is important to investigate the performance of different WMA technologies separately to properly understand the performance of WMA mixtures with RAP. This study presents an extensive and systematic analysis of the available literature regarding WMA and RAP mixtures to properly understand the behavior of RAP mixtures with different WMA technologies. The analysis concludes that the use of RAP in WMA could improve the overall performance in terms of rutting, moisture resistance and workability. However, fatigue performance is only improved in WMA with organic additives while further studies are recommended to evaluate the low temperature performance.