About the project

In the context of global climate urgency, the field of sustainable road infrastructures is experiencing a notable surge in interest and investment. One of the key focal points is the widespread adoption of recycling practices. Techniques such as pavement recycling, which involves the reuse of existing road materials, significantly contribute to the reduction of construction‐related carbon emissions. By minimizing the need for new raw materials and reducing waste disposal, recycling initiatives contribute to the circular economy framework, fostering resource efficiency and environmental sustainability.

Innovations in recycling technologies have enabled the efficient recovery and reintegration of materials, paving the way for cost‐effective and environmentally conscious road maintenance practices. An initiative in this regard is the MAX‐RAP project aimed at instigating a transition towards a decarbonized road infrastructure system through the optimisation of asphalt pavement recyclability. By leveraging the collective expertise of researchers and industry partners, MAX‐RAP endeavours to develop innovative solutions that optimise the recyclability of asphalt pavements.

A few specific aspects addressed by this project are as follows:

• As the binder ages, due to volatilization and other phenomena, the proportion of the maltene fraction reduces in the aged binder. This creates an imbalance in its composition and results in a blend that does not deliver the desired performance. Thus, the first step in recycling is to decide whether the given RAP binder is amenable for recycling. This study attempts to check whether a given RAP is suitable for recycling.
• The RAP obtained from field is considerably stiff due to the aging of the binder and the effect of wheel loads. The aged binders, when used in larger proportions or have higher extents of aging, necessitate the use of rejuvenators. For larger proportions of RAP, the use of such rejuvenators may not be feasible as when added in large proportions, these blends are known to exhibit poor aging susceptibilities. Thus, alternatives to rejuvenators are being explored.
• There are many challenges in hot mix recycling with a majority of them dealing with assessing the characteristics of the RAP binder present in RAP. A few of them include quantification of the available binder from RAP and its blending with fresh binder. If the RAP binder is separated from the mixture, then it is possible to do a straightforward mix design with suitable adjustments to account for the increased stiffness of the RAP binder. The possibilities of separation of RAP binder from RAP on a large scale is being explored.
• The proportion of constituents is expected to differ based on the extent of recyclability of the binders. For binders with a higher degree of aging, rejuvenators may have to be added, while the same may not be necessary for binders with a lower extent of aging. The proportioning of blend constituents will be carried out accordingly such that the resultant binder exhibits target rheological properties with maximum utilisation of RAP. In addition, appropriate laboratory testing methods will be used to investigate the performance of the recycled blends.

The outcomes of this project are expected to result in a framework for recycling binders based on the extent of recyclability of the blends with consideration to maximum utilisation of RAP and incorporation of alternatives to commercially available rejuvenators.