基于纳米粒子的PVA纤维水泥基复合材料力学性能及耐久性能研究

Based on compressive strength test, uniaxial tensile test, four points bending test, three point bending test of notched beam specimens and a series of durability tests, the effects of nano-SiO2 on the mechanical properites of compressive properties, tensile properties, bending resistance, fracture properties of PVA fiber reinforced cementitious composite containing nano-particles will be investigated. The effect rules of the dosage of nano-SiO2 on the mechanics performance parameters, the fracture parameters, the durability evaluation indices and the stress-strain relationships will be revealed. Besides, the effects of nano-SiO2 on the durability of freezing resistance, resistance to carbonizing, anti-permeability and shrinkage performance of the composite will be studied. Meanwhile, the failure mechanism, fracture damage law and durability degradation mechanism of the composite will be expounded. In addition, the constitutive relation model and the durability forecast model will be estabilished. Applying microscopic test method, the microstructure of PVA fiber reinforced cementitious composite containing nano-particles will be studied, and the destruction face will be observed and analyzed. Furthermore, applying the view of energy, combining macroscopic and mesoscopic view, combining damage and fracture view, the couple effect mechanism of nano-SiO2 and PVA fiber on the mechanical properties and durability of cementitious composite will be studied. This study has great theoretical significance and practical value to enrich and develop the basic theory of fiber reinforced cementitious composite. The expected results may has great contribution on the application of PVA fiber reinforced cementitious composite containing nano-particles in the practical engineering project.

通过抗压试验、单轴拉伸试验、四点弯曲试验、预切口梁三点弯曲试验和耐久性试验，探明纳米SiO2对纳米粒子PVA纤维水泥基复合材料抗压性能、抗拉性能、抗弯性能、断裂性能等力学性能和抗冻性、抗碳化性、抗渗性、收缩性能等耐久性的影响，揭示纳米SiO2掺量对各力学性能参数、断裂参数、耐久性评价指标及应力应变特性影响的规律，阐明复合材料的破坏机理、断裂损伤规律及耐久性能退化机理，建立复合材料的本构关系模型，并建立复合材料的耐久性预测模型。利用微观测试方法对纳米粒子PVA纤维水泥基复合材料的微观结构进行研究，对试件破坏面进行观测分析，应用能量观点以及宏观与细观、损伤与断裂相结合等观点，从微观层次上探明纳米SiO2与PVA纤维耦合作用对水泥基复合材料力学性能及耐久性能影响的作用机理。本项目对丰富和发展纤维水泥基复合材料基本理论，推动纳米粒子PVA纤维水泥基复合材料的工程应用具有重要的理论意义和实用价值。

随着水泥基复合材料研究的深入以及纳米材料制造成本的降低，纤维增强纳米水泥基复合材料将会是未来结构工程中应用潜力极大的一种高性能建筑材料。本项目通过坍落度和坍落扩展度试验对水泥基复合材料的工作性能进行了研究，分析了纤维掺量和纳米材料掺量对水泥基材料工作性的影响；分别通过抗压强度和抗拉强度试验研究了纳米粒子和纤维材料对纤维增强纳米水泥基复合材料抗压和抗拉性能的影响；通过三点弯曲韧性试验，分别测得纳米粒子改性纤维增强水泥基复合材料小梁试件的初裂荷载、最大荷载和初裂挠度，分析了纳米粒子对纤维增强水泥基复合材料弯曲韧性的影响，并分析了复合材料在弯曲荷载作用下的破坏机理；通过预切口梁式试件的三点弯曲试验，分别测得了不同纳米粒子掺量纤维水泥基复合材料的断裂韧度、断裂能等断裂参数，分析了纳米粒子对纤维增强纳米水泥基复合材料各断裂参数和荷载位移全曲线的影响，分析了纤维增强纳米水泥基复合材料的断裂破坏机理；通过耐久性试验，分析了纳米粒子和纤维材料对纤维增强纳米高性能混凝土各种耐久性影响的作用机理，得出了得出了纳米粒子和纤维掺量对各耐久性评价指标影响的规律；利用微观测试方法对纤维增强纳米水泥基复合材料进行了微观分析，分析了纳米粒子与纤维材料在水泥基复合材料内部的分布特点，分析了掺加纳米粒子和纤维材料的水泥基复合材料增强增韧的力学机理，从微观层次上详细探讨纳米材料与材料纤维耦合作用对水泥基复合材料力学性能及耐久性能影响的作用机理；本项目研究成果将会为纤维增强纳米水泥基复合材料的推广应用提供可靠的理论依据，具有广阔的应用前景。