Lightweight concrete with fly ash aggregates and graphene oxide: performance and durability

The growing demand for concrete and depletion of natural aggregates necessitate sustainable alternatives, particularly for structural lightweight applications. While sintered fly ash coarse aggregates (SFCA) offer a viable solution for low-density concrete (LDC), their mechanical and durability limitations restrict broader structural use. This study addresses this gap by investigating the effectiveness of ultra-low dosages (0.01–0.05% by cement weight) of graphene oxide (GO) in enhancing SFCA-based LDC. Results demonstrate that GO significantly improves the mechanical performance of SFCA-based LDC, upgrading its strength class from M25 to M55, while maintaining acceptable workability and setting characteristics. Durability performance was also enhanced, with up to 40% improvement in sulphate resistance, 45% in chloride resistance, and a 35% reduction in permeable porosity at 28 days. Microstructural examination made through scanning electron microscopy, energy dispersive X-ray, and X-ray diffraction analyses confirmed the formation of a denser and more stable matrix due to GO incorporation. Additionally, a performance-based economic assessment indicated an approximate 10% cost advantage. The findings establish GO-modified SFCA-based LDC as a high-performance, durable, and sustainable alternative for structural applications, highlighting its potential to reduce both resource consumption and environmental impact.