Synergistic Enhancement of Polyurethane Foam Concrete Using Nano-Graphene, Silica, and Alumina: A Multi-Scale Study on Strength, Durability, and Microstructure

This study explores the development of polyurethane foam concrete (PUFC) enhanced with nano-silica, nano-alumina, and graphene oxide to address the material’s inherent limitations in strength and durability while improving its sustainability performance. PUFC is widely recognized for its lightweight and thermal insulation properties, yet its low compressive and flexural capacity restricts structural applications. To overcome these drawbacks, a series of mixes were prepared with varying nanoparticle dosages, and their mechanical, durability, and microstructural properties were systematically evaluated. The results revealed that the optimized ternary blend (M2) achieved the highest compressive strength of 7.0 MPa at 28 days, representing a 42.6% improvement over the control mix. Enhanced flexural and tensile strengths were also observed, attributed to the synergistic effects of refined pore structure, accelerated hydration, and improved crack bridging. Durability indicators, including water absorption, chloride permeability, and freeze–thaw resistance, showed significant improvements in nanomodified mixes, confirming the role of nanoparticles in densifying the matrix. Microstructural observations further linked gel-pore dominance with better eco-efficiency, reducing embodied carbon while improving sustainability indices. Overall, the findings highlight the potential of nanomodified PUFC as a lightweight, durable, and environmentally responsible material for modern construction applications.