It has been established that the addition of synthetic fibers like polypropylene (PP) to ultra-high performance concrete (UHPC) enhances the latter’s thermal spalling resistance. The key for this is the thermal mismatch between embedded fibers and matrix as a result of the expansion of PP fibers with temperature. This manuscript explores the effect of natural fibers (replacing traditional PP fibers) on compressive strength, hot permeability, and spalling resistance of UHPC. Different dosages (3, 5 and 10 kg/m³) of jute fibers are used for this purpose. The findings are critical as they oppose the mechanism of thermal spalling resistance established for synthetic fibers in UHPC. Natural fibers swell by absorbing water (during the casting of UHPC and during their service life) and shrink upon exposure to warm and high temperatures. The deswelling and shrinkage of natural fibers at high temperatures create spaces between fibers and matrix, which could influence permeability at those temperatures. This suggests that percolation of fibers is critical in the case of jute as opposed to PP fibers. It was found that a dosage of 10 kg/m³ of jute fibers is required for eliminating spalling of UHPC as opposed to 3 kg/m³ for PP fibers. Additionally, preliminary efforts are put in to investigate the short-term durability of the samples and changes in properties of UHPC with jute fibers.

已经确定的是，在超高性能混凝土（UHPC）中添加诸如聚丙烯（PP）之类的合成纤维可增强后者的抗热剥落性。这样做的关键是由于PP纤维随温度的膨胀而导致嵌入纤维与基质之间的热失配。该手稿探讨了天然纤维（代替传统的PP纤维）对UHPC的抗压强度，热渗透性和抗剥落性的影响。不同剂量（3、5和10 kg / m ³黄麻纤维用于此目的。这一发现是至关重要的，因为他们反对为UHPC中的合成纤维建立抗热剥落性的机制。天然纤维通过吸收水而膨胀（在UHPC浇铸过程中以及使用寿命期间），并在暴露于高温和高温时收缩。天然纤维在高温下的膨松和收缩会在纤维和基质之间形成空间，这可能会影响这些温度下的渗透性。这表明，与黄麻纤维相比，黄麻对纤维的渗透至关重要。发现消除UHPC剥落所需的黄麻纤维用量为10 kg / m ³，而不是3 kg / m ³用于PP纤维。此外，还进行了初步努力来研究样品的短期耐久性以及黄麻纤维对UHPC性能的影响。