An experimental study was carried out to evaluate the effect of several fibers on the mechanical properties, drying shrinkage, and microstructural characteristics of alkali-activated kaolin binders. Four different types of fibers were evaluated in this study: polypropylene (PP) fiber, discontinuous structural synthetic (DSS) fiber, brass-coated steel (BCS) fiber, and hooked steel (HS) fiber. The fibers were added to the alkali-activated kaolin at a volume fraction of 0%, 0.5%, 1%, and 1.5%. The experimental results revealed that the compressive strength of alkali-activated binder increased by about 60% when 1% of PP fiber is added, whereas the addition of HS fiber substantially enhanced the flexural strength (more than 200% when 1.5% fiber volume content is added). BCS and HS fibers were found to more effective compared to PP and DSS fibers in maintaining the binder integrity prior to high temperatures exposure. All fiber-reinforced alkali-activated composites yielded lower drying shrinkage (≤450 microstrains), where HS fiber was found to effectively prevent the shrinkage of the binder (≤60 microstrains). The microstructural investigation revealed good interfacial bonding between the alkali-activated binder and the fibers.

中文翻译：

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纤维种类和含量对碱活化高岭土力学性能和收缩特性的影响

进行了一项实验研究，以评估几种纤维对碱活化高岭土粘合剂的机械性能、干燥收缩率和微观结构特性的影响。本研究评估了四种不同类型的纤维：聚丙烯 (PP) 纤维、不连续结构合成 (DSS) 纤维、黄铜涂层钢 (BCS) 纤维和钩钢 (HS) 纤维。将纤维以 0%、0.5%、1% 和 1.5% 的体积分数添加到碱活化高岭土中。实验结果表明，添加 1% PP 纤维时，碱活化粘合剂的抗压强度提高了约 60%，而添加 HS 纤维则显着提高了抗弯强度（当纤维体积含量为 1.5% 时，抗压强度提高了 200% 以上）添加）。与 PP 和 DSS 纤维相比，发现 BCS 和 HS 纤维在高温暴露前保持粘合剂完整性方面更有效。所有纤维增强的碱活化复合材料的干燥收缩率都较低（≤450 微应变），其中 HS 纤维被发现可有效防止粘合剂的收缩（≤60 微应变）。微观结构研究揭示了碱活化粘合剂和纤维之间良好的界面结合。