超高性能混凝土中纤维作用效应研究综述

Review on the Effects of Fiber Action in Ultra High-Performance Concrete

超高性能混凝土(UHPC)是一种具有超高强度、高耐久性的新型水泥基复合材料,其应用仍受到包括造价高、韧性不足、高温抗爆裂性能差等因素的影响,相关研究表明上述因素均与内掺纤维有关。为进一步促进纤维对UHPC性能的优化,推进UHPC在工程领域中的应用,通过梳理国内外近年来相关研究成果,总结钢纤维形状和长径比、不同纤维类型、纤维混杂和纤维取向分布对UHPC相关性能的影响,结果表明:钢纤维具备优异的力学性能且来源广泛,仍为UHPC中主要使用的纤维,异形钢纤维改善UHPC抗拉、抗弯等性能效果更好,但工作性能会相应地降低,建议钢纤维掺量采用2%~3%;不同类型纤维混掺存在最优组合,非钢纤维掺量普遍不超过0.5%;纤维平行于主拉应力方向分布能够提升纤维桥接作用的有效性,随机分布的纤维有效性降到了30%,对于纤维取向控制方法尚不成熟,需要进一步完善方法实现在非实验室条件下纤维定向分布的实际尺寸。

Ultra high-performance concrete(UHPC)is a new type of cement-based composite material with ultra-high strength and durability,which has become a hot research topic in the field of engineering.Overall,its application is still affected by related factors,including high cost,insufficient toughness,and poor high-temperature anti burst performance.Relevant studies have shown that these factors are all related to the addition of fibers.In order to further promote the optimization of fiber performance in UHPC and promote the application of UHPC in the engineering field,the influence of steel fiber shape and aspect ratio,different fiber types,fiber mixing,and fiber orientation distribution on UHPC related properties was summarized by reviewing relevant research results at home and abroad in recent years.The results showed that steel fiber has excellent mechanical properties and is still the main fiber used in UHPC with a wide range of sources.Deformed steel fiber improves the tensile strength of UHPC The bending resistance and other performance effects are better,but the working performance will be correspondingly reduced.It is recommended to use a steel fiber content of 2%to 3%;There is an optimal combination for mixing different types of fibers,and the content of non-steel fibers generally does not exceed 0.5%;The distribution of fibers barallel to the main tensile stress direction can enhance the effectiveness of fiber bridging,and the effectiveness of randomly distributed fibers is reduced to 30%.The method for controlling fiber orientation is not yet mature,and further improvement is needed to achieve the actual size UIIPC of fiber directional distrilnition under non laboratory conditions.