高温中纤维纳米混凝土力学性能及其计算方法

发布时间：2018-02-01 15:13

本文关键词： 混凝土高温纤维纳米二氧化硅纳米碳酸钙力学性能强度计算模型应力-应变关系弯曲韧性 SEM XRD　出处：《郑州大学》2017年博士论文　论文类型：学位论文

【摘要】：本文是国家自然科学基金项目“纤维纳米混凝土及其高温中和高温后性能研究”(51178434)的主要内容之一。通过纤维纳米混凝土配合比试验、常温和高温中纤维纳米混凝土力学性能试验、SEM微观结构观测和XRD物相分析,重点研究纤维纳米混凝土配合比,常温和高温中纤维纳米混凝土抗压性能、劈拉性能、抗剪性能和弯曲韧性,纳米材料增强机理和纤维纳米混凝土高温劣化机理,建立相应的计算模型。主要内容如下:(1)通过22组配合比试验,研究纳米材料掺量、混凝土强度等级和钢纤维体积率对浆体富余系数和砂浆富余系数的影响,提出基于工作性的纤维纳米混凝土配合比设计方法。与传统配比设计方法相比,该配合比设计方法试验量小,适用性广,其结果可方便地换算成各因素对用水量和砂率的影响,并能够与传统配合比设计方法相衔接。(2)通过13组配合比共156个纤维纳米混凝土试件的抗压、劈拉、抗剪和弯曲韧性试验,研究了钢纤维体积率、纳米材料掺量和混凝土强度等级对纤维纳米混凝土抗压、劈拉和抗剪性能以及弯曲韧性的影响,分别建立了考虑纤维和纳米材料影响的纤维纳米混凝土抗压强度、劈拉强度、抗剪强度和抗折强度的计算模型,提出了适合纤维纳米混凝土特点的韧性评价方法。(3)通过10组配合比共300个150mm×150mm×300mm纤维纳米混凝土棱柱体试件的高温中轴压试验,研究了温度、钢纤维体积率和纳米材料掺量对高温中纤维纳米混凝土抗压强度和轴压本构关系的影响,提出了考虑温度、纤维和纳米材料影响的高温中纤维纳米混凝土立方体抗压强度、棱柱体峰值应力、峰值应变和初始弹性模量的计算公式,建立了高温中纤维纳米混凝土轴压本构关系数学模型。(4)通过10组配合比共150个150mm×150mm×150mm纤维纳米混凝土标准立方体试件的高温中劈拉试验,研究了温度、钢纤维体积率和纳米材料掺量对高温中纤维纳米混凝土劈拉强度、峰值变形、劈拉荷载-横向变形曲线下包面积等的影响,提出了考虑温度、纤维和纳米材料影响的高温中纤维纳米混凝土劈拉强度计算公式以及高温中纤维纳米混凝土劈拉韧性评价方法。(5)通过10组配合比共150个100mm×100mm×400mm纤维纳米混凝土梁式试件的四点弯曲试验,研究了温度、钢纤维体积率和纳米材料掺量对高温中纤维纳米混凝土抗折强度、峰值挠度、荷载-挠度曲线下包面积等的影响,提出了考虑温度、纤维和纳米材料影响的高温中纤维纳米混凝土抗折强度计算公式以及高温中纤维纳米混凝土弯曲韧性评价方法。(6)通过SEM微观结构观测和XRD物相分析,研究了温度和纳米材料对纤维纳米混凝土微观结构和矿物组成的影响,探讨了纳米材料对纤维纳米混凝土微观性能的影响机理及纤维纳米混凝土高温劣化机理。
[Abstract]:This paper is one of the main contents of the project of National Natural Science Foundation, "study on Fiber Nanoconcrete and its performance after High temperature and High temperature". Mechanical Properties Test of Fiber Nanoconcrete at Room temperature and High temperature SEM microstructure observation and XRD phase analysis, focusing on the mix ratio of fiber nanocrystalline concrete. At room temperature and high temperature, the compressive resistance, splitting tensile property, shear resistance and flexural toughness of fiber nano-concrete, the mechanism of nano-material strengthening and the mechanism of high-temperature deterioration of fiber nano-concrete are discussed. The main contents are as follows: (1) through 22 groups of experiments, the content of nanomaterials was studied. The influence of strength grade of concrete and volume ratio of steel fiber on the surplus coefficient of mortar and mortar, a new design method based on workability of fiber nano-concrete mixture ratio is put forward, which is compared with the traditional design method. This design method has the advantages of small test quantity and wide applicability. The results can be easily converted into the influence of various factors on water consumption and sand rate. The volume ratio of steel fiber was studied through the compression, splitting, shearing and bending toughness tests of 156 fiber nanoconcrete specimens with 13 groups of blending ratios. The effects of the content of nano-material and the strength grade of concrete on the compressive, splitting and shearing properties and flexural toughness of fiber nanocrystalline concrete. The calculation models of compressive strength, splitting tensile strength, shear strength and flexural strength of fiber nano-concrete considering the influence of fiber and nano-material were established respectively. The toughness evaluation method suitable for fiber nanocrystalline concrete is put forward. The axial compression tests at high temperature of 300 150 mm 脳 150 mm 脳 300 mm fiber reinforced nanocrystalline (FRC) prisms were carried out in 10 groups. The effects of temperature, volume ratio of steel fiber and content of nano-material on the compressive strength and axial compression constitutive relationship of fiber nanocrystals at high temperature were studied, and the temperature was considered. The calculation formulas of cube compressive strength, peak stress of prism, peak strain and initial elastic modulus of fiber and nanomaterials at high temperature. A mathematical model of axial compression constitutive relation of fiber nanocrystalline concrete at high temperature was established. The splitting tensile tests of 150 standard cube specimens of 150 mm 脳 150 mm 脳 150 mm fiber nanocrystals were carried out in 10 groups. The effects of temperature, volume ratio of steel fiber and content of nano-material on splitting tensile strength, peak deformation and area under splitting load-transverse deformation curve of nano-fiber concrete in high temperature were studied. Formula for calculating splitting tensile strength of Fiber-Nanoconcrete under High temperature influenced by Fiber and Nanomaterials and Evaluation method of splitting tensile toughness of Fiber-Nanoconcrete at High temperature. The four-point bending tests of 150 specimens of 100mm 脳 100mm 脳 400mm fiber nanocrystalline concrete beams were carried out in 10 groups. The effects of temperature, volume ratio of steel fiber and content of nano-material on flexural strength, peak deflection, load deflection curve and area under load-deflection curve of fiber nanocrystals were studied, and the temperature was considered. Calculation formula of flexural strength of fiber nanocrystals under high temperature and flexural toughness evaluation method of fiber nanocrystals under the influence of fibers and nanomaterials. SEM microstructure observation and XRD phase analysis were carried out. The effects of temperature and nanomaterials on the microstructure and mineral composition of fiber nanocrystalline concrete were studied. The mechanism of influence of nano materials on the microstructure of fiber nano concrete and the degradation mechanism of fiber nano concrete at high temperature were discussed.
【学位授予单位】：郑州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU528

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