纤维矿渣微粉混凝土高温性能试验研究

发布时间：2018-09-04 14:52

【摘要】：通过1232个不同尺寸的纤维矿渣微粉混凝土试件在常温、高温中和高温后力学性能试验,并结合微观测试及机理分析,重点探讨温度、矿渣微粉掺量、聚丙烯纤维掺量、钢纤维体积率和混凝土强度等级对纤维矿渣微粉混凝土力学性能的影响,主要研究内容和结论如下： 1.进行了纤维矿渣微粉混凝土常温力学性能试验研究。结果表明,矿渣微粉和钢纤维使纤维矿渣微粉混凝土抗压强度、劈拉强度和变形、抗折强度和变形均有不同程度提高；聚丙烯纤维对纤维矿渣微粉混凝土抗压强度、弹性模量和劈拉变形均有不同程度改善；随混凝土强度等级提高,纤维矿渣微粉混凝土劈拉强度和变形、抗折强度和变形均有不同程度提高。根据对试验结果的统计分析,建立了考虑矿渣微粉掺量、聚丙烯纤维掺量和钢纤维体积率影响的纤维矿渣微粉混凝土常温抗压强度、劈拉强度、抗折强度和弹性模量的计算模型。 2.进行了纤维矿渣微粉混凝土高温后扫描电镜分析和机理分析。结果表明,温度、矿渣微粉、聚丙烯纤维、钢纤维和混凝土强度等级对纤维矿渣微粉混凝土烧失率有不同程度影响。随着温度升高,纤维矿渣微粉混凝土内部水分逐渐蒸发分解,水泥浆体以及骨料与水泥浆体的界面过渡区内C-S-H凝胶,钙矾石AFt晶体和氢氧化钙Ca(OH)2晶体等水泥水化物的形貌、状态和数量以及孔隙与裂缝均发生了不同程度地变化,其高温爆裂和微观组织高温损伤发展过程与其组织内部水的分解汽化与迁移过程有关。 3.进行了纤维矿渣微粉混凝土高温中和高温后力学性能试验研究。结果表明,高温作用使纤维矿渣微粉混凝土抗压强度比、劈拉强度比、抗折强度比和弹性模量比均有不同程度降低。矿渣微粉和聚丙烯纤维掺量变化对纤维矿渣微粉混凝土高温抗压强度比、劈拉强度比、抗折强度比和弹性模量比影响较小；随钢纤维体积率增大,纤维矿渣微粉混凝土高温抗压强度比、劈拉强度比和抗折强度比有不同程度提高,其中劈拉强度比和抗折强度比的提高幅度较大。对比分析高温和常温试验研究结果,建立了纤维矿渣微粉混凝土高温抗压强度、劈拉强度、抗折强度和弹性模量的计算模型。 4.测试了纤维矿渣微粉混凝土高温变形性能,系统分析了温度、矿渣微粉掺量、聚丙烯纤维掺量、钢纤维体积率和混凝土强度等级对纤维矿渣微粉混凝土抗压、劈拉和弯曲变形的影响,建立了考虑温度、矿渣微粉掺量、聚丙烯纤维掺量和钢纤维体积率影响的纤维矿渣微粉混凝土高温受压应力-应变曲线方程。
[Abstract]:Through the mechanical properties tests of 1232 concrete specimens with fiber slag powder at room temperature, high temperature and high temperature, combined with microscopic test and mechanism analysis, the temperature, the content of slag powder and the content of polypropylene fiber were discussed. The effects of volume ratio of steel fiber and strength grade of concrete on the mechanical properties of fiber slag micro-powder concrete are studied. The main contents and conclusions are as follows: 1. The mechanical properties of fiber slag micro-powder concrete at room temperature were studied. The results show that the compressive strength, splitting tensile strength and deformation, flexural strength and deformation of fiber slag micro-powder concrete can be improved by slag micro-powder and steel fiber, and polypropylene fiber can improve the compressive strength of fiber slag micro-powder concrete. The elastic modulus and split tensile deformation are improved in varying degrees, and with the increase of concrete strength grade, splitting tensile strength and deformation, flexural strength and deformation of fiber slag micro-powder concrete are improved in varying degrees. Based on the statistical analysis of the test results, the compressive strength and splitting tensile strength of concrete with fine powder of slag, polypropylene fiber and volume ratio of steel fiber at room temperature were established. Models for calculating flexural strength and modulus of elasticity. 2. SEM analysis and mechanism analysis of fiber slag micro-powder concrete after high temperature were carried out. The results show that temperature, slag micro-powder, polypropylene fiber, steel fiber and concrete strength grade have different effects on the burning loss rate of fiber slag micro-powder concrete. With the increase of temperature, the internal moisture of fiber slag micro-powder concrete gradually evaporates and decomposes, and the morphology of cement hydrates such as C-S-H gel, ettringite AFt crystal and calcium hydroxide Ca (OH) 2 crystal in the transition zone between cement paste and aggregate and cement paste is obtained. The state and quantity as well as the pore and fracture have changed in different degrees. The process of high temperature burst and microstructure damage at high temperature is related to the water decomposition and vaporization and migration process. The mechanical properties of fiber slag fine powder concrete after high temperature and high temperature were studied. The results show that the compressive strength ratio, splitting tensile strength ratio, flexural strength ratio and elastic modulus ratio of fiber slag micro-powder concrete are decreased by high temperature. The change of slag powder and polypropylene fiber content has little effect on high temperature compressive strength ratio, splitting tensile strength ratio, flexural strength ratio and elastic modulus ratio of fiber slag micro powder concrete. The ratio of high temperature compressive strength, split tensile strength and flexural strength of fiber slag micro-powder concrete has been improved to some extent, and the ratio of splitting tensile strength and flexural strength has been greatly improved. The calculation models of high temperature compressive strength, splitting tensile strength, flexural strength and elastic modulus of fiber slag micro-powder concrete are established by comparing and analyzing the experimental results of high temperature and normal temperature. 4. The deformation properties of fiber slag micro-powder concrete at high temperature were tested. The compression resistance of fiber slag micro-powder concrete was analyzed systematically by temperature, slag powder content, polypropylene fiber content, volume ratio of steel fiber and strength grade of concrete. Under the influence of splitting and bending deformation, the stress-strain curve equation of fiber slag micro-powder concrete under high temperature compression was established considering the influence of temperature, slag powder content, polypropylene fiber content and volume ratio of steel fiber.
【学位授予单位】：郑州大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528

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