Development of hybrid coating systems for concrete steel structures emphasizing fire protection and long-term durability

The integrity and safety of concrete‐steel structures are crucial in modern construction, as these systems face harsh environmental conditions and potential fire exposure. This review explores recent advancements in hybrid protective coatings designed to enhance fire resistance, mechanical strength, and long-term durability. Traditional coatings often fall short in extreme conditions; however, hybrid systems—integrating nanomaterials, polymers, and functional fillers—offer synergistic performance improvements. Central to these coatings is the use of advanced materials such as graphene, carbon nanotubes, and layered silicates, which significantly enhance thermal stability, flame retardancy, adhesion, and crack resistance. The review emphasizes nano-enabled fire-retardant strategies that combine physical insulation and chemical action. Additives like phosphorus-based compounds, expandable graphite, and intumescent agents support char formation and heat shielding, maintaining structural integrity during fire events. At the same time, ceramic and metallic nanofillers, polymer reinforcement, and crosslinking mechanisms are used to improve resistance to impact, abrasion, and environmental degradation. The development of multifunctional and smart coatings with self-healing, self-cleaning, and environmental responsiveness receives special attention. These include graphene–polymer and ceramic–polymer hybrids, as well as green coatings designed with bio-based or low-carbon materials for sustainability. This review highlights the vital role of material innovation and hybrid formulation strategies in developing next-generation coatings that protect infrastructure from both mechanical and thermal stressors.