A Comprehensive Review Of Copper Slag Integration In Pavement Construction: Sustainable Material Substitution, Environmental Perspectives, And Performance Enhancement

Flexible pavements are the most common road infrastructure worldwide due to their cost-effectiveness and ability to efficiently distribute traffic loads through layered systems. Traditionally, they rely heavily on natural resources such as sand, gravel, crushed stone, and bituminous binders. However, growing infrastructure demand and environmental concerns have exposed limitations of these conventional materials. The primary issue is the depletion of high-quality natural aggregates, particularly sand and gravel, caused by extensive mining. This overexploitation threatens ecosystems, drives up material costs, and creates supply chain uncertainties. Moreover, the production and use of bituminous binders and Portland cement are energy-intensive, contributing significantly to greenhouse gas emissions and contradicting global sustainability targets. Performance challenges further complicate pavement design. Conventional materials often lead to rutting, fatigue cracking, and thermal distress, reducing service life under increasing traffic loads and extreme climatic conditions. Poor drainage and filtration in base or subbase layers can cause moisture accumulation, structural weakening, and early pavement failures. The migration of fines from subgrade soils to granular layers clogs drainage paths, further decreasing durability.