## 7 Overview and Prospective Developments  
It is possible to conclude that tear-off scrap shingles (TOSS) are generally added to asphalt mixtures using the dry mixing method (relatively more convenient and economical), even if the wet mixing method, i.e., bitumen modification with RAS (either involving an extracted RAS binder or fine RAS particle addition), is used to determine the suitable blending and rheological properties of the modified binder. Based on a number of literature studies, RAS at up to 5% by weight of aggregate/asphal mixtures were found to be relatively suitable to improve the performance properties of asphalt mixtures, both in laboratory studies and field applications. When properly dosed and combined with specific additives, RAS could increase the stiffness, stability, and high-temperature performance properties of asphalt mixtures without compromising the fatigue and thermal crack resistance.  
On the other hand, there are still many aspects that need further research, such as (i) the influence of the mixing time, mixing temperature, and RAS type and size on the final mix properties; (ii) the possible inclusion of RAS in porous asphalts, warm-mix asphalts, and other \"special mixtures\"; and (iii) the use of innovative rejuvenators (e.g., bio-additives) to enhance the ductility of RAS-modified asphalts.  
In particular, the following conclusions are drawn.  
* Comprehensive research studies have not been performed on the RAS mixing time, RAS size (either particles \(<\) 12.5 mm or ultrafine powder of RAS), and mixing temperature (HMA, WMA, CMA) to obtain a relatively optimized modified mixture in terms of performance properties.
* Methodologies (such as the use of specific additives) able to optimize the fatigue and thermal crack resistance without compromising the high-temperature performance require detailed study.
* Due to the small number of conflicting experimental findings, there is a need to investigate the RAS-modified asphalt mixtures' moisture susceptibility, as well as the resistance against freeze-thaw cycles of RAS-modified bituminous mixtures.
* The addition of RAS into porous asphalt mixtures has not been studied yet.
* Very few studies exist about the combination of RAS and warm-mix technologies; thus, RAS-modified WMA requires extensive investigation, taking into account the different available warm technologies.
* There is the need to deeply investigate the rheological and chemophysical properties of RAS-modified asphalt mastics.
* There is still a lack of plant-scale validation of RAS-modified bituminous mixtures to develop policies at a national level towards the use of RAS in sustainable asphalt pavements.
* There is a need to prepare a clear road map (either for the wet or dry mixing method) related to the addition of RAS in asphalt mixtures during real plant production.  
Conceptualization, S.H. and M.P.; methodology, S.H. and E.P.; validation, E.P. and M.P.; investigation, S.H. and E.P.; data curation, S.H. and M.P.; writing--original draft preparation, S.H.; writing--review and editing, E.P. and M.P.; visualization, S.H.; supervision, E.P. and M.P.; project administration, M.P and E.P. All authors have read and agreed to the published version of the manuscript.  
Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data used in this manuscript were taken from the cited literature. Conflicts of Interest: The authors declare no conflicts of interest.