Abstract The study aims to improve flexural properties of ultra-high-performance concrete (UHPC) prepared with different steel fiber volumes by controlling the rheological properties of the suspending mortar. Welan gum and high-range water reducer were incorporated to control rheology. Optimum rheological properties led to enhanced fiber distribution. Fiber distribution coefficient was proposed and considered to characterize fiber dispersion and orientation. For UHPC with 1%, 2%, and 3% fiber volumes, the highest flexural performance was obtained with mortars having plastic viscosities of 36, 52, and 66 Pa·s, respectively. Beyond these values, further increase in viscosity resulted in greater air entrapment and lower mechanical properties. Prediction model for flexural strength that considers a correlation between fiber dispersion and flexural-to-tensile strength ratio of the UHPC was developed. Viscosity of UHPC mortar was shown to be a reliable indicator to determine flexural-to-tensile strength ratio, and hence predict flexural strength of UHPC.

中文翻译：

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不同纤维含量超高性能混凝土的流变控制

摘要 本研究旨在通过控制悬浮砂浆的流变性能，提高不同钢纤维用量的超高性能混凝土（UHPC）的抗弯性能。加入威兰胶和高效减水剂以控制流变性。最佳的流变特性导致增强的纤维分布。提出并考虑了光纤分布系数来表征光纤色散和取向。对于具有 1%、2% 和 3% 纤维体积的 UHPC，使用塑性粘度分别为 36、52 和 66 Pa·s 的砂浆获得最高的弯曲性能。超过这些值，粘度的进一步增加导致更大的空气滞留和更低的机械性能。开发了弯曲强度预测模型，该模型考虑了 UHPC 的纤维分散和弯曲拉伸强度比之间的相关性。UHPC 砂浆的粘度被证明是确定抗弯强度比的可靠指标，从而预测 UHPC 的抗弯强度。