Maximizing the Application of RAP in Asphalt Concrete Pavements and Its Long-Term Performance: A Review

Abstract

The use of recycled asphalt pavement (RAP) materials in asphalt concrete pavements (ACP) brings significant cost and environmental benefits. In practice, however, the amount of RAP readily available far exceeds the amount being utilized in ACPs, which still leaves the problem of excess RAP in the environment partially solved. Additionally, ACPs containing RAP materials (i.e., RAP-ACPs) can still be landfilled after they have reached the end of their useful life, which may restore the original environmental waste problem. To address these, researchers have demonstrated different ways to maximize the application of RAP in ACPs. Among them, the use of RAP in pavement preventive maintenance (PPM) treatments and the repeated recycling of RAP-ACPs (i.e., RnAP) are specifically discussed in this review. It is envisaged that, by promoting these two practices, the application and benefits of RAP can be further maximized to improve sustainability. This review also discusses the long-term behavior of RAP-ACP, which is crucial to inspire confidence in the wider application of RAP in ACP. Studies on RAP-PPM have shown that virgin PPM treatments can successfully accommodate RAP materials by adjusting their mix design. So far, research on RnAP has been limited to how multiple-recycling affects the performance properties of the blends, showing improvements in rutting resistance and moisture susceptibility but little effect on linear viscoelasticity and cracking. Overall, the lack of sufficient research is considered to be the biggest challenge in facilitating the implementation of these two sustainable RAP technologies. Little or nothing is known about the bonding mechanisms between RAP and fresh PPM binders, the molecular and chemical changes in RnAP binders, or the functional performance characteristics, actual pavement performance, and long-term performance of both RAP-PPM and RnAP blends. An understanding of these aspects is very relevant to maximize and continue the beneficial reuse of RAP in ACPs while safeguarding human and environmental health.

Multi-Objective Optimization for Sustainable Pavement Maintenance Decision Making by Integrating Pavement Image Segmentation and TOPSIS Methods

“…The carbon emissions of the asphalt pavement maintenance phase include three subphases: the raw material phase, the transportation phase, and the construction phase. The carbon emissions generated by them can be expressed by Equation (5).…”

“…For example, processes such as asphalt patching can lead to increased emissions due to the energy-intensive nature of the rehabilitation process [4]. While the use of recycled asphalt pavement or bio-based binders has the potential to reduce emissions, they have not yet gained widespread adoption, mainly due to concerns about their pavement performance [5]. Given these challenges, an important issue facing the maintenance of asphalt pavements is how to efficiently and objectively conduct road surface damage detection and propose maintenance solutions that are both low-carbon and economical.…”

Investigation of Fatigue Life by Four Point Bending Test of Recycled Asphalt Pavements

“…Little or nothing is known about the binding mechanisms between RAP and fresh PPM binders, the molecular and chemical changes in RnAP binders, or the functional performance characteristics, actual pavement performance, and long-term performance of both RAP-PPM and RnAP blends. Understanding these aspects is crucial to maximize and sustain the beneficial reuse of RAP in ACPs while protecting human and environmental health [6].…”

Development of Pavement Material Using Crumb Rubber Modifier and Graphite Nanoplatelet for Pellet Asphalt Production

“…The presence of this minor pavement damage can lead to the progressive development of a higher degree of pavement deterioration and the potential for traffic accidents. When these small road damages (i.e., potholes) and urgent repairs are required, emergency restoration must be performed abruptly to prevent traffic problems [ 5 , 6 ]. Currently, conventional heated asphalt concrete is difficult to produce in small quantities and the plant operation must be stopped in the case of rain.…”