Mechanical properties and durability of steel fiber-reinforced fly ash geopolymer concrete containing granite waste and agricultural waste ashes

Abstract

To alleviate environmental issues, agricultural wastes such as rice husk ash (RHA) and sugarcane bagasse ash (SCBA) were used to produce high-strength steel fibre-reinforced geopolymer concrete (HSFRGC). Additionally, granite waste, an industrial waste, was used to fully replace natural fine aggregate. The objective of this study was to investigate the effects of RHA, SCBA, and steel fibre on the engineered properties of HSFRGC. RHA or SCBA was added as an additive at 0%, 1%, 3%, and 5% by weight of fly ash. To improve flexural performance, steel fibres were used at 0%, 0.5%, and 1% by volume of concrete. The properties investigated included workability, compressive strength, elastic modulus, flexural behaviour and toughness, chloride resistance, and microstructure of HSFRGC. The results indicated that adding 1% RHA or SCBA could enhance the microstructure of the geopolymer matrix, leading to densification, as confirmed by microstructural investigations. This enhancement resulted in improved mechanical performance and durability. Furthermore, incorporating 1% steel fibres along with RHA or SCBA improved the compressive strength and elastic modulus, meeting the criteria for high-strength concrete according to ACI 363R. In terms of durability, chloride penetration was mitigated, with or without steel fibres, by incorporating 1% RHA or SCBA into the geopolymeric system. Finally, considering environmental impact and cost-effectiveness, incorporating 1% RHA or SCBA and 0.5% steel fibre demonstrated a suitable balance between improved mechanical properties and addressing cost and environmental concerns.