Waste-to-Resource Paving: A Scientometric Knowledge Mapping, Systematic Review, and SWOT analysis of Recycled Concrete Aggregates Applications in flexible pavements: A decarbonization and circular economy prospect

The increase in the rate of depletion of natural aggregate resources and the rise in the volume of construction and demolition waste (CDW) are critical challenges in the development of sustainable pavement infrastructure. Recycled concrete aggregate (RCA) seems to have appeared as a technically viable and strategic way for the development of sustainable flexible pavement infrastructure in the context of the circular economy, sustainability, and decarbonization. The current review paper uses scientometric, performance analysis, and SWOT analysis for the review of global trends in the use of RCAs and their performance in the circular economy and de-carbonization potential. A total of 107 peer-reviewed published works, as obtained from Web of Science, Scopus, and ScienceDirect (2010–2025), were analysed with co-authorship network analysis, keyword co-occurrence method, and bibliographic coupling. From the results, China, the United States, and India are found to be at the forefront of primary hubs, while mixture optimization, mechanical performance, durability, and LCA are seen to be prominent thematic clusters. Experimental results show that, when processed and graded appropriately, RCA can exhibit equivalent or better stiffness, resilient modulus, and rutting resistance; however, moisture susceptibility and compositional variation are major limitations. It was observed that, based on the RCA quality, source, and gradation, the optimal substation range for RCA in flexible pavement ranges from 10–50%. For surface layers, around 10 to 20% is recommended to minimize rutting and durability issues. For the binder layers, a replacement level of 20 to 30%. For the base and the subbase layers, 30 to 50% can be considered, as the structural performance of these layers is less sensitive to the properties of the aggregates. From a sustainability perspective, RCA substitution can lead to a 15–35% reduction in embodied carbon emissions, and considerable volumes of CDW can be prevented from ending up in landfills, thus directly addressing the SDGs 8, 9, 11, 12, 13, and 15. Thus, RCA can be considered a means of addressing decarbonization and circular materials, directly linking structural performance with climate-responsive strategies. The review shows that RCA should not only be considered as a recycled aggregate approach, but also as a material change strategy with the potential to achieve infrastructure development and decarbonization, circular economy, resource preservation, and pavement sustainability. It is, therefore, important for future studies to place more emphasis on full-scale field verification, performance modeling, and techno-economic optimization.