Comparisons between closed-loop and straight metal fibres inconcrete

Concretes containing closed-loop fibres and conventional straight fibresare compared for workability, bond strength, compressive strength, tensile strength, flexural strength and toughness. The concept of spacing is treated briefly. Tests indicate that all fibres have little effect until after significant cracking occurs. After cracking, closed loops offer much better integrity than straight fibres. Closed-loop fibres reduce the variability ofboth compressive and tensile strengths.