Recycled aggregate concrete (RAC) has been gaining a large interest in recent years due to the depletion of natural aggregates and environmental protection requirements. To improve the ductility of RAC for structural applications and to avoid corrosion risks involved with utilising steel fibres, this study proposes a deflection-hardening hybrid fibre-reinforced recycled aggregate concrete (FRRAC) by combining newly developed macro-basalt fibre (BF, 0.67 % by volume) and recycled macro-polypropylene fibre (PF, 0.67 % by volume). Its fresh, static and dynamic mechanical properties were investigated and compared with the mix containing macro-BF only (1.34 % by volume). A Ø 100 mm split Hopkinson pressure bar (SHPB) system was used to determine the dynamic mechanical properties in compression and tension. The hybrid FRRAC retained up to 90 % of its average first peak load at 3.5 mm crack width and showed better cracking bridging performance under dynamic splitting tension than the specimens with the same volume of macro-BF. Empirical formulae for dynamic increase factors and energy absorption capacities against varying strain rates have also been proposed for the newly developed hybrid FRRAC.

中文翻译：

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挠度硬化混合纤维增强再生骨料混凝土的物理力学性能


近年来，由于天然骨料的枯竭和环保要求，再生骨料混凝土（RAC）引起了人们的广泛关注。为了提高 RAC 在结构应用中的延展性，并避免使用钢纤维带来的腐蚀风险，本研究提出了一种结合新开发的粗玄武岩纤维（BF，0.67%）的挠曲硬化混合纤维增强再生骨料混凝土（FRRAC）按体积计）和再生大聚丙烯纤维（PF，按体积计 0.67%）。研究了其新鲜、静态和动态机械性能，并与仅含有大分子 BF（体积比 1.34%）的混合物进行了比较。使用直径 100 毫米的分体式霍普金森压力棒 (SHPB) 系统来确定压缩和拉伸的动态机械性能。混合 FRRAC 在 3.5 mm 裂缝宽度下保留了高达 90% 的平均第一峰值载荷，并且在动态劈裂张力下比具有相同体积宏观 BF 的试件表现出更好的裂缝桥接性能。对于新开发的混合 FRRAC，还提出了针对不同应变率的动态增加因子和能量吸收能力的经验公式。