Most literature has focused on the effect of shrinkage-reducing admixture (SRA) in shrinkage mitigation resistance of concrete. This study aims to examine the impact of SRA on the efficiency of macro synthetic fibers (MSF) in enhancing the flexural post-cracking behavior of fiber-reinforced super workable concrete (FR-SWC). A comparative analysis of the influence of fiber combinations on the flexural post-cracking behavior of beams is also included. Results showed that a higher dosage of SRA, particularly at 5 % by mass of binder, had a noticeable negative impact on flexural post-cracking performance of beams while exhibiting positive effect on workability and shrinkage reduction. However, incorporating low dosages of SRA (1.25 % by mass of binder) did not have a significant impact on the ability of MSF. This was attributed to the reduction of the MSF-matrix bond strength caused by a significant delay in cement hydration. The characteristics of selected MSF type, including length and surface roughness had a positive effect on the post-cracking performance of FR-SWC, regardless of SRA dosage. The notched beams made with 100 % MSFA outperformed those made with fiber combination of 25 % MSFA and 75 % MSFB. Beams made with 100 % MSFA showed 55 % higher residual flexural tensile strength, 49 % higher equivalent flexural tensile strength, 50 % higher fracture energy, and 35 % higher equivalent flexural strength ratio compared to beams made with fiber combination of 25 % MSFA and 75 % MSFB. Therefore, the negative effect of SRA on the flexural-post cracking behavior can be partial compensated by adjusting MSF content and combinations.

中文翻译：

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减缩外加剂影响宏观合成纤维增强超易加工混凝土的抗弯后裂解性能


大多数文献都集中在减少收缩外加剂 （SRA） 对混凝土抗收缩性的影响。本研究旨在检验 SRA 对宏观合成纤维 （MSF） 在增强纤维增强超级可加工混凝土 （FR-SWC） 的弯曲后开裂行为方面的影响。此外，还对纤维组合对梁的弯曲后开裂行为的影响进行了比较分析。结果表明，较高的 SRA 剂量，尤其是 5% 的粘合剂用量，对梁的弯曲后开裂性能有明显的负面影响，同时对可加工性和减少收缩表现出积极影响。然而，掺入低剂量的 SRA（粘合剂质量的 1.25%）对 MSF 的能力没有显着影响。这归因于水泥水化显着延迟导致 MSF -基体粘合强度降低。无论 SRA 用量如何，所选 MSF 类型的特性（包括长度和表面粗糙度）对 FR-SWC 的后开裂性能都有积极影响。由 100% MSFA 制成的缺口梁优于由 25% MSFA 和 75% MSFB 的纤维组合制成的缺口梁。与使用 25% MSFA 和 75% MSFB 的纤维组合制成的梁相比，由 100% MSFA 制成的梁的剩余弯曲拉伸强度提高了 55%，等效弯曲拉伸强度提高了 49%，断裂能量提高了 50%，等效弯曲强度比提高了 35%。因此，SRA 对弯曲后开裂行为的负面影响可以通过调整 MSF 含量和组合来部分补偿。