Integrating Green Nanotechnology in Civil Engineering: Enhancements, Socioeconomic Impacts, and Future Directions

The rapid expansion of nanotechnology in civil engineering has generated extensive research on nano-modified materials, sensing systems, water treatment, and energy-efficient infrastructure. However, existing reviews commonly examine these applications in isolation and rarely integrate engineering performance with lifecycle safety, economic feasibility, and implementation readiness. This review addresses this gap through a civil-engineering-focused synthesis of five principal application domains: nano-enhanced construction materials and coatings, structural health monitoring, water and wastewater treatment, energy-efficient buildings, and hazard-resilient urban infrastructure. The evidence indicates that nano-enabled systems can improve mechanical and durability-related properties, reduce permeability and thermal transport, enhance contaminant removal, and enable highly sensitive infrastructure monitoring. Nevertheless, the magnitude and reliability of these benefits depend strongly on nanomaterial type and dosage, dispersion quality, exposure conditions, testing protocols, and system boundaries. Six recurring barriers to practical implementation are identified: high production costs, scale-up limitations, uncertain long-term durability, insufficient standardization, integration difficulties, and unresolved toxicity and end-of-life risks. The distinctive contribution of this review is an integrated assessment framework that connects measurable civil-engineering performance with lifecycle environmental impacts, economic feasibility, broader socioeconomic implications, regulatory readiness, and field-scale adoption. The findings demonstrate that improved technical performance alone cannot establish the environmental credentials of a nano-enabled solution; credible evaluation must also consider embodied energy and emissions, occupational exposure, nanoparticle release and persistence, recyclability, and lifecycle cost. Future progress therefore requires standardized testing, long-term field validation, transparent lifecycle assessment, and application-specific safety regulation.