Asphalt Recycling Technologies: A Review on Limitations and Benefits

Recycling of asphalt pavements gained popularity in 1970s due to the rapidly increasing cost and reducing supply of oil and hence - bitumen. However, presently there are other reasons to develop this technology, the main being the ability to utilize non-renewable resources. Sustainability of asphalt pavement construction can only be ensured if we are able to utilize the available reclaimed asphalt pavement (RAP) material completely in the new construction. Another potential advantage is the mutual benefit of using RAP in conjunction with warm mix asphalt (WMA). This is due to compensation of hardened binder from RAP with softer binder of WMA. For such mixes, significant energy savings can be realized due to the lower mixing and compaction temperature as well as due to lesser efforts required for compaction. This paper summarises several approaches that can be adopted to maximize the amount of RAP material in asphalt mixtures. In addition, the current recycling practices implemented in the industry are discussed to identify the main reason behind the lacking confidence in using high RAP content in mixes. The environmental and economical benefits of high rate of recycling are also discussed. Finally, the possible research directions that will allow to incorporate high proportion of RAP without compromising the performance of pavement are discussed.