Sustainable High-Strength Lightweight Concrete: Synergistic Effects of Cenospheres and Nano-Coating on Durability and Performance

This study investigates the development of sustainable, high-performance lightweight concrete by incorporating cenospheres hollow microspheres from fly ash as a 10% replacement for fine aggregate and enhancing it with a lithium silicate-based nano-coating (Nitoflor LH). Comprehensive testing revealed that the 10% cenosphere mix significantly improved mechanical properties, achieving a 7.3% increase in 28-day compressive strength (22.41 MPa vs. 21.73 MPa) and notable gains in split tensile and flexural strength over conventional concrete. Durability assessments demonstrated a 16.5% reduction in sorptivity, indicating lower water absorption, and a substantial decrease in chloride ion permeability in the cenosphere-based mix. The application of the nano-coating provided a further 10.7% boost in 28-day compressive strength (reaching 24.80 MPa) and drastically reduced both sorptivity and chloride penetration by over 40% compared to the uncoated control. These results underscore a powerful synergy: cenospheres densify the internal microstructure, while the nano-coating seals the surface. This combined approach successfully produces a structural lightweight concrete with superior strength, enhanced durability, and greater energy efficiency, offering a viable sustainable solution for the modern construction industry.