混杂纤维对超高性能混凝土增强增韧影响的研究

发布时间：2018-01-17 03:35

本文关键词：混杂纤维对超高性能混凝土增强增韧影响的研究　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：本论文主要研究了混杂纤维对超高性能混凝土(Ultra High Performance Concrete,UHPC)强度和韧性的影响。首先,通过比较两种异形钢纤维(波纹形和端钩型)分别与中尺寸的平直钢纤维复掺后UHPC的强度和韧性,优选出较好的异形钢纤维。然后,将优选出的钢纤维分别与聚乙烯纤维、玄武岩纤维和中尺寸的平直钢纤维复掺,研究纤维双掺对UHPC强韧化的效果,寻找最佳纤维双掺组合;并在此基础上,将该最佳双掺组合分别与聚乙烯纤维、玄武岩纤维和小尺寸的平直钢纤维进行三掺,探索不同尺度纤维混杂对UHPC增强和增韧的影响。最后,将粗骨料以体积取代水泥砂浆的方式掺入强韧化效果最佳的三尺度混杂纤维UHPC中,分析粗骨料掺量对UHPC强度和韧性的影响。试验测试方法包括抗压强度、劈裂抗拉强度、断裂能和四点弯曲性能。试验结果表明,与波纹形钢纤维和中尺寸平直钢纤维复掺相比,端钩型钢纤维和中尺寸平直钢纤维复掺UHPC的强韧化效果更佳,这是因为端钩型状比波纹形状与混凝土基质的粘结性能更好。就两尺度纤维组合而言,钢-聚乙烯纤维复掺UHPC的增强增韧效果优于钢-玄武岩纤维和钢-钢纤维复掺的情况;对于三尺度纤维组合,钢-钢-聚乙烯纤维的增强增韧效果优于钢-钢-玄武岩纤维和钢-钢-钢纤维的复掺。对比不同尺度纤维混掺UHPC的力学性能发现,当纤维总掺量相同时,三尺度纤维复掺效果略优于两尺度纤维的复掺,钢-钢-聚乙烯纤维组合UHPC比钢-聚乙烯纤维组合的抗压强度、劈拉强度和断裂能分别提高了 6%、3%和10%;而两尺度纤维复掺效果优于单掺纤维,钢-聚乙烯纤维组合比单掺聚乙烯纤维的抗压强度、劈拉强度和断裂能分别提高了 5%、58%和2.1倍。UHPC的抗压强度和劈裂抗拉强度均随粗骨料掺量的增加而逐渐降低,且劈裂抗拉强度的下降幅度非常大,当粗骨料的掺量达到30%,UHPC的断裂能下降45%。
[Abstract]:In this paper, the effect of hybrid fiber on strength and toughness of Ultra High Performance reinforced concrete (UHPC) is studied. By comparing the strength and toughness of two kinds of profiled steel fibers (corrugated and end hook) and medium size plain straight steel fibers, the better special-shaped steel fibers were selected. The excellent steel fiber was mixed with polyethylene fiber basalt fiber and medium size straight steel fiber respectively to study the effect of fiber double admixture on the strength and toughness of UHPC and to find the best combination of fiber double admixture. On the basis of this, the optimum combination was tri-doped with polyethylene fiber, basalt fiber and small size straight steel fiber respectively. The effect of fiber mixing on UHPC strengthening and toughening was explored. Finally, the coarse aggregate was added into the three-scale hybrid fiber UHPC which had the best toughening effect by volume replacement of cement mortar. The influence of coarse aggregate content on the strength and toughness of UHPC is analyzed. The test methods include compressive strength, splitting tensile strength, fracture energy and four-point bending property. Compared with corrugated steel fiber and medium size straight steel fiber, the strength and toughness effect of end hook steel fiber and medium size straight steel fiber mixed with UHPC is better than that of corrugated steel fiber and medium size straight steel fiber. This is because the end hook shape is better than the corrugated shape than the concrete matrix. In the case of two-scale fiber combination. The reinforcing and toughening effect of steel / polyethylene fiber mixed with UHPC is better than that of steel basalt fiber and steel steel fiber. For three-scale fiber combinations. The reinforcing and toughening effect of steel-steel-polyethylene fiber is better than that of steel-steel-basalt fiber and steel-steel-steel fiber. When the total fiber content is the same, the effect of three-scale fiber blending is slightly better than that of two-scale fiber, and the compressive strength of steel-steel-polyethylene fiber combination UHPC is higher than that of steel-polyethylene fiber combination. The splitting tensile strength and fracture energy increased by 6% and 10% respectively. The effect of two-scale fiber blending is better than that of single-doped fiber, and the compressive strength, splitting strength and fracture energy of steel-polyethylene fiber combination are 5% higher than that of single-doped polyethylene fiber, respectively. The compressive strength and splitting tensile strength of 58% and 2.1-fold. UHPC decreased gradually with the increase of coarse aggregate content, and the extent of splitting tensile strength was very large, when the content of coarse aggregate reached 30%. The fracture energy of UHPC decreases by 45%.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

【参考文献】