钢纤维直径及组合对UHPC性能的影响

The influence of steel fiber diameter and combination on the property of UHPC

通过选用4种直径的平直型镀铜微丝钢纤维,设计并制备了22组常温养护型超高性能混凝土(UHPC)试验,研究了镀铜微丝钢纤维不同直径、直径组合及掺量对UHPC流动度、抗压强度、抗折强度、抗拉强度的影响.结果表明:各直径钢纤维掺量不超过1.0%时,对UHPC流动度基本无影响,随着掺量增加,流动度呈下降趋势,抗压强度、抗折强度、抗拉强度都呈增长趋势;掺量达到2.0%后,增长趋势放缓,放缓幅度与钢纤维直径成反比;大直径与小直径钢纤维组合能提高UHPC的流动度及抗压强度,缩小抗压强度标准差;刚度较大的大直径钢纤维更利于UHPC抗折强度的提高,而小直径的钢纤维因其具有更大的黏结比表面积,更利于抗拉强度的提高.

22 groups of room temperature curing UHPC tests were designed and prepared by selecting four kinds of diameter of flat copper coated microwire steel fiber.The effects of different diameter,diameter combination and dosage of copper coated microwire steel fiber on the fluidity,compressive strength,flexural strength and tensile strength of UHPC were studied.The results show that the fluidity of UHPC is basically unaffected when the amount of steel fiber is less than 1.0%.With the increase of the amount of steel fiber,the fluidity shows a downward trend,and the compressive strength,flexural strength and tensile strength all show an increasing trend.When the amount of steel fiber reaches 2.0%,the increasing trend slows down,and the slowing down range is inversely proportional to the diameter of steel fiber.The combination of large diameter and small diameter steel fiber can improve the fluidity and compressive strength of UHPC and reduce the standard deviation of compressive strength.The large diameter steel fibers with larger rigidity are more conducive to the improvement of UHPC flexural strength,while small diameter steel fibers with larger bonding specific surface area are more conducive to the improvement of the tensile strength.