Harnessing Sludge-Derived Materials for Circular and Sustainable Asphalt Pavement Engineering: A Bibliometric, Systematic Review, and Strategic SWOT Analysis

The expansion of industries and the construction of additional wastewater treatment infrastructure have led to an exponential generation of wastewater treatment sludge, posing serious long-term environmental harm. As a result, pavement engineers have explored the potential use of sludge-derived materials (SDMs) to promote a circular economy and fulfill the United Nations Sustainable Development Goals. The present work is focused on the feasibility of using various SDMs, sewage sludge ash, alum sludge, industrial sludge, and petroleum as safe constituents of asphalt pavements. A combined scientometric and systematic review, supported by a SWOT analysis, was conducted on publications from 2010 to 2025. The USA and China, followed by India, were the most prolific contributors. SDMs have been shown to enhance the stiffness, durability, and resistance to moisture damage and rutting of asphalt pavements. The use of a petroleum sludge modifier was found to lower energy demand by 20% and carbon emissions by 15–39%, indicating positive environmental and economic implications. The cost of treating petroleum sludge is approximately 144 €/ton, whereas disposal costs range from 250 to 300 €/ton. Differences in sludge composition, treatment procedures, and the absence of common standards are the main obstacles to the widespread application of these materials; more structured technical and legislative initiatives are required.