Fresh and mechanical properties of concrete reinforced with novel wavy macro-basalt fibres for sustainable structural applications

Steel fibres are widely used to improve the mechanical performance of concrete but are associated with high density, corrosion susceptibility and increased material demand. This study experimentally evaluates the effectiveness of newly developed wavy macro-basalt fibres as an alternative reinforcement for structural concrete. Fifteen concrete mixes incorporating steel fibres, chopped basalt fibres and wavy macro-basalt fibres with aspect ratios of 36 and 60 were prepared. Workability, compressive strength, splitting tensile strength, flexural strength and shear strength were evaluated. The results showed that workability decreased with increasing fibre dosage for all fibre types. At 7 days, all fibres improved compressive strength, whereas MBF60 maintained or slightly improved the 28-day strength. MBF60 achieved the greatest improvement in splitting tensile strength, reaching 93% and 70% above the control concrete at 7 and 28 days, respectively. It also increased flexural strength by 22%, matching steel fibres while requiring approximately 70% less fibre content. In shear, MBF60 achieved a 20% strength increase using over 50% less fibre content than steel fibres. The findings demonstrate that fibre geometry and aspect ratio strongly influence reinforcement efficiency, and that wavy macro-basalt fibre, particularly MBF60, provides a corrosion-resistant and mechanically efficient alternative for structural concrete applications.