Warm mix asphalt (WMA) is an energy-saving and environmental-friendly technology with a broad prospect for application in highway construction. When compared with hot mix asphalt (HMA), WMA reduces the mixing and compaction temperatures (by 25–30°C) and hence reduction in energy consumption and emissions of harmful gases while maintaining the workability of HMA. In this study, three different additives, namely, Sasobit (organic wax additive), Evotherm (emulsion-based chemical additive) and Zycotherm (anti-stripping chemical additive) were evaluated for their laboratory performance under repeated weathering actions. HMA and WMA laboratory samples for Marshall stability, indirect tensile strength and tensile strength ratio were cast and subjected to 0, 2, 4, 6 and 8 freeze and thaw cycles (F&T cycles) in numbers and then tested. A comparative study was performed among HMA and three WMA mixes (control and weathered), that is, Sasobit-WMA (S-WMA), Evotherm-WMA (E-WMA) and Zycotherm-WMA (Z-WMA) to analyse the trend of variation in strength and properties with varying F&T cycles. Aggregate coating and compactibility were also analysed.

The rheological behavior of recycled asphalt binders is important in the design of the optimum content of reclaimed asphalt pavement (RAP) material to be used in highway recycling projects. In this study, oscillatory tests were performed on recycled binders of varying RAP concentrations. The complex modulus master curves were constructed using the time–temperature superposition principle. The zero shear viscosities (ZSVs) were estimated using the Carreau–Yasuda model on the complex viscosity master curves for all the recycled binder combinations. It was found that the activation energy of flow changed linearly from 115.1 to $185.8\mathrm{kJ}/\mathrm{mol}$ with an increase in the RAP content, whereas ZSV varied exponentially with an increase in the RAP content. A good correlation was found between the ZSV and the Superpave rutting parameter ($G^{*}/\sin \delta$ ). An equation was derived to predict the $G^{*}/\sin \delta$ at any RAP concentration and temperature. For practical use, a $G^{*}/\sin \delta$ contour plot approach is introduced to calculate directly the maximum and minimum RAP content for any target binder grade suitable for the construction site. cA noticeable change in rheological behavior of recycled binders was observed on either side of the 40% RAP incorporation level.

Roads are the national assets of a country. Once they are non-functional, they can be recycled to serve the next design life. Flexible pavements are the predominant type of pavement all over the world. The distressed flexible pavement material can be termed as Reclaimed Asphalt Pavement (RAP) material. The most common percent of RAP in the recycling process is 20% only. For higher incorporation of RAP material, there is uncertainty in the performance of RAP-HMA mixture. Design Mixture of RAP incorporated HMA technology depends on criteria’s like the viscosity of aged RAP extracted binder, dosages of recycling agents, overheating of RAP material and method of intrusion of RAP material in plant production units etc. The fields cum laboratory studies have found rutting, fatigue and moisture susceptibility as major concerns in this technology. The uses of rejuvenators have been found to improve the fatigue resistance of asphalt mixture but its over-dosages may impact rutting resistance. Hence, a balanced mixture design method which involves performance evaluation of recycled mixture is required. This paper discusses the mixture design of RAP-HMA pavement.