This paper presents an investigation on the effects of four different fibers (polypropylene (PP), polyvinyl alcohol (PVA), recycled polypropylene (RPP), and steel (S) fibers) on the fracture behaviour of ambient-cured fly ash geopolymer concrete (GPC). The four fibers were added into GPC by both mono at 1.0% volume and hybrid combinations with steel fiber at 0.5% of each other type of fiber. The full-field strain distribution and the crack mouth opening displacement (CMOD) were monitored by digital image correlation (DIC) technology. The results reveal that adding fibers was effective in enhancing the fracture performance and hindering the cracking behaviour of GPC. Furthermore, 1.0% volume steel fiber exhibited to be most advantageous in enhancing the flexural strength by 100%, flexural toughness by 4000%, fracture energy by 3897%, and critical stress intensity factor by 98.8%. GPC with 1.0% volume PP fiber exhibited a characteristic length of 7909 mm, improving the characteristic length of GPC by about 2925%. Additionally, the CMOD was found to have a strong linear relationship with deflection which is unaffected by other factors. The presence of fibers significantly enhanced the ultimate strain. The steel fibers exhibited better performance in hindering the crack propagation. The fracture process zone (FPZ) characteristics differed between specimens with non-metallic and steel fibers, with the latter exhibiting more tortuous shapes and multiple cracks. Notably, a hybridization of steel and non-metallic fibers proves better than mono non-metallic fibers in improving strength, toughness, and ductility. This research provides valuable insights for concrete design and the selection of appropriate fibers based on specific requirements.

中文翻译：

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使用数字图像相关技术比较含有四种不同纤维的单一和混合组合的常温固化地质聚合物混凝土的断裂性能

本文研究了四种不同纤维（聚丙烯（PP）、聚乙烯醇（PVA）、再生聚丙烯（RPP）和钢（S）纤维）对常温养护粉煤灰地质聚合物混凝土断裂行为的影响。凝胶渗透色谱）。这四种纤维以 1.0% 体积的单纤维和各类型纤维 0.5% 的与钢纤维的混合组合添加到 GPC 中。采用数字图像相关（DIC）技术监测全场应变分布和裂口张开位移（CMOD）。结果表明，添加纤维可有效增强GPC的断裂性能并阻碍其开裂行为。此外，1.0%体积钢纤维最有利于将弯曲强度提高100%，弯曲韧性提高4000%，断裂能提高3897%，临界应力强度因子提高98.8%。添加1.0%体积PP纤维的GPC表现出特征长度为7909mm，将GPC的特征长度提高了约2925%。此外，还发现 CMOD 与挠度具有很强的线性关系，且不受其他因素的影响。纤维的存在显着增强了极限应变。钢纤维在阻碍裂纹扩展方面表现出更好的性能。非金属和钢纤维试样的断裂过程区（FPZ）特征不同，后者表现出更曲折的形状和多个裂纹。值得注意的是，钢和非金属纤维的混合在提高强度、韧性和延展性方面比单一非金属纤维更好。这项研究为混凝土设计和根据特定要求选择合适的纤维提供了宝贵的见解。