【作者】 张伟；

【导师】 王生武；

【作者基本信息】 大连交通大学 ， 工程力学， 2008， 硕士

【摘要】 混凝土材料因抗压强度高、耐久性好、成本低等特点在建筑工程中得到了广泛应用,但作为一种脆性材料,混凝土的抗拉强度远低于抗压强度,这在很大程度上限制了其应用范围。近年来采用纤维掺入混凝土来解决这一问题取得了较好的效果,特别是具有轻质、耐腐蚀、易于均匀分散等优点的聚丙烯纤维,更是有着良好的应用前景。另外,由于在混凝土中掺入粉煤灰可以带来技术、经济、环境、社会等诸多方面的重要效益,因此对粉煤灰混凝土的研究己成为水泥与混凝土科学中的重要研究领域。随着混凝土在土木工程中的应用越来越广泛,应用范围也扩展到对抗疲劳、抗冲击等有较高要求的领域,这些工程在服役期内经常承受随机或周期性反复荷载,因此,研究聚丙烯纤维对混凝土及粉煤灰混凝土抗疲劳性能的影响显得极为重要。综合上述情况,本文选用了一种性能优良的国产改性聚丙烯纤维,在两种混凝土基材下研究了纤维对混凝土性能的影响及其作用机理。首先,以普通混凝土为基材,研究了在不同纤维掺量下该纤维对混凝土静强度及弯曲疲劳性能的影响,建立了各掺量下改性聚丙烯纤维增强混凝土材料的弯曲疲劳方程,探讨了疲劳性能的影响规律,通过对比分析确定了纤维的最佳掺量。然后,以20%等量取代水泥的粉煤灰混凝土为基材,进一步研究了该纤维对粉煤灰混凝土性能的影响及其作用机理。改性聚丙烯纤维对普通混凝土性能的影响:纤维掺入后,混凝土的抗压强度变化不大,但在一定掺量范围内,劈裂强度、抗折强度、及弯曲疲劳性能均有较为显著的提高。随着纤维掺量的增加,纤维在混凝土中出现了一定程度的成束现象而影响了混凝土的性能。综合考虑静强度及疲劳性能试验结果,该纤维在混凝土中的最佳掺量为0.10%(体积分数)。改性聚丙烯纤维对粉煤灰混凝土性能的影响:纤维掺入粉煤灰混凝土,纤维与粉煤灰除发挥各自的作用外,还能优势互补,形成良好的协同效应,从而大幅提高混凝土的劈裂强度、抗折强度、及弯曲疲劳性能。而且随掺量的增加,纤维没有出现明显的成束现象,掺量越高,混凝土性能的提高幅度越大。更多还原

【Abstract】 Concrete material use widely in construction project because of its merits including higher compressive strength,better durability and lower cost. But,as brittle material,concrete has much lower tensile strength as against of its compressive strength.This performance weakness of concrete has limited its application scope to great extent.Recently,mixing fiber in the concrete has made good progress in solving this problem,especially polypropylene fiber,which offers the advantage of light,corrosion resistance,evenly distributed and so on,has a good application prospect.Moreover,the research of fly ash in concrete has become a great important research area in the science of cement and concrete because mixes fly ash in concrete can bring important benefit in many aspects such as technology,economy,environment,society and so on.The application scope of concrete has expanded to high request domain of anti-fatigue and anti-impact along with its application getting more and more widespread in civil engineering.These projects withstand stochastic or periodic load frequently,research of fatigue performance of polypropylene fiber in concrete and fly ash concrete appears the great importance.Synthesized the situations above,this paper has selected a kind of fine performance modified polypropylene fiber which is made in China,studied performance and fundamental which was influenced on fiber in two different kinds of parent concrete.Firstly,taking plain concrete as parent concrete,studied static intensity and flexural fatigue performance which was influenced on the variation of fiber in volume,established the flexural fatigue equation of modified polypropylene fiber in concrete,searched the effects rule of flexural fatigue performance and found the best level of fibers in volume.Secondly,taking concrete with 20% (by mass) fly ash as parent concrete,further study has been made to find out the performance influence and the effects rule of fiber and fly ash in concrete.Effects of modified polypropylene fibers on performance of plain concrete:mixing a certain amount of modified polypropylene fibers into concrete has little influence upon compressive strength of concrete,but increased cleavage strength,flexural strength and flexural fatigue performance of concrete greatly.With the advance of fiber mixing level’s increase,some fiber bundles can be found in concrete to certain extent which affects the performance of concrete.Considered both static intensity and flexural fatigue performance,0.10% of modified polypropylene fibers in volume is the best level mixing in concrete. Effects of modified polypropylene fibers on performance of concrete with fly ash:Mixing modified polypropylene fibers into fly ash concrete,fibers and fly ash has a good cooperative effect,further enhanced the flexural fatigue performance of concrete.Moreover,along with fiber’s increase,there are no obvious fiber bundles in concrete,cleavage strength,flexural strength and flexural fatigue performance of concrete with fly ash increase greatly.更多还原