钢纤维掺量对超高性能混凝土性能影响的试验研究

Experimental Study on the Influence of Steel Fiber Content on the Performance of UHPC

通过纤维掺量的调整以及规范的制备流程,研究不同强度系列的超高性能混凝土制备技术,并对比分析了不同强度下超高性能混凝土的新拌浆体性能、力学性能以及耐久性能。结果表明:控制纤维体积掺量在1.5%~5.0%范围,可实现系列化UHPC制备;纤维显著影响UHPC新拌浆体扩展度及容重,但对含气量影响较小;UHPC抗压强度、抗弯强度、拉伸强度与纤维掺量呈正相关,静弹性模量与纤维掺量无明显作用关系;系列UHPC抗压强度均有明显的尺寸效应;混凝土拉伸性能与试件的尺寸及加载方式有关,劈拉抗拉评价方法数据离散性小,而单轴抗拉评价方法试验数据离散性高,结果准确获取难度大;UHPC氯离子扩散系数低于普通混凝土2个数量级,具有较好的耐久性能,可满足超高强、高耐久的性能要求。

By adjusting the fiber content and regulating the preparation process,the preparation technology of different strength series of ultra-high performance concrete is studied,and the properties of fresh slurry,mechanical properties and durability of ultra-high performance concrete under different strengths are also compared and analyzed.The results show that the preparation of series UHPC can be realized by controlling the volume fraction of fibers in the range of 1.5%~5.0%.Steel fibers have a significant influence on the expansion and bulk density of fresh UHPC paste,but have a little effect on the air content.The compressive strength,flexural strength and tensile strength of UHPC are positively correlated with the content of steel fiber,while the static elastic modulus has no obvious effect on the content of steel fiber.The compressive strength of series UHPC has an obvious size effect.The tensile properties of concrete are related to the size and loading mode of specimens.The data of the splitting tensile strength evaluation method are less discrete,while the data of the uniaxial tensile strength evaluation method are more discrete,and it is difficult to obtain the results accurately.The chloride diffusion coefficient of UHPC is two orders of magnitude lower than ordinary concrete,and it has better durability.It meets the performance requirements of super high strength and durability.