<p>This comprehensive review examines how industrial waste materials&mdash;specifically waste metallic fibres (WMF) and waste polypropylene fibres (WPF)&mdash;can be converted into high-performance concrete reinforcement. Waste fibres improve concrete behaviour by arresting crack propagation through pinching forces at crack tips, transforming brittle failure into a ductile, energy-absorbing response. Short fibres provide superior compressive strength; long fibres enhance flexural performance and post-cracking ductility; hybrid (multimodal) systems combining both yield optimal results. Waste polypropylene fibre-reinforced composites demonstrate post-cracking behaviour and load-carrying capacity that, in many cases, exceed waste metallic fibre performance despite lower density. Waste fibre-reinforced concrete (WFRC) reduces material costs by 20&ndash;40%, addresses waste management challenges, and delivers enhanced structural performance&mdash;transforming environmental liabilities into competitive advantages.</p>

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