Development of Optimised Basalt FRP Macrofibre-Reinforced Concrete with Evaluation of Fresh, Mechanical and Durability Performance

Abstract This paper investigates the properties of an emerging fibre-reinforced concrete (FRC) incorporating basalt fibre-reinforced polymer macrofibres (BFRPmf), as dispersed, non-metallic reinforcement. The study aimed to develop BFRPmf-reinforced concrete (BFRPmfRC or BmfRC) with optimised fresh, mechanical, and durability performance by evaluating three BFRPmf types at four volume fractions (Vf = 0.25%, 0.5%, 0.75%, 1%) in a self-compacting concrete (SCC) matrix, yielding 12 mixes. Fresh properties were assessed using slump flow, V-funnel, and J-ring tests. Hardened mechanical properties were measured through compressive strength, tensile splitting strength, and direct (uniaxial) tensile tests (DTT). Durability indicators included volume of permeable voids (VPV), electrical resistivity (ER), and chloride migration coefficient (CMC). To capture full-range tensile behaviour without premature fracture, a tapered dog-bone specimen was designed for DTT, with strain monitored by digital image correlation (DIC). The 12 BmfRSCC mixes were benchmarked against a plain SCC reference. Results showed that BFRPmfs with higher slenderness and effective count reduced workability beyond 0.5% Vf but enhanced direct tensile strength by up to 70%. With homogeneous fibre dispersion, post-cracking ductility also increased, allowing tensile strains of 20–22%. Compressive strength remained within ± 10% of the reference. The optimal dosage, determined through analysis of variance (ANOVA), was 0.5% Vf, balancing rheological and mechanical behaviour. Flexural residual strength testing guided the selection of the most effective fibre type for structural trials. Durability results from tests on slab cores confirmed that, at optimal dosage, BFRPmf improved both mechanical and durability properties, highlighting its potential as a sustainable, corrosion-resistant alternative to steel reinforcement.