混杂纤维混凝土抗硫酸盐侵蚀性能的实验研究

发布时间：2018-08-03 20:54

【摘要】：环境引起的混凝土结构耐久性失效主要表现在钢筋锈蚀和混凝土腐蚀。混凝土的腐蚀又分为化学腐蚀、冻融破坏以及碱骨料反应,而硫酸盐侵蚀又是化学腐蚀中是最复杂、危害性最大的一种环境侵蚀作用。混凝土受硫酸盐侵蚀后在宏观上表现为膨胀、开裂、溶蚀、剥落及强度下降等,影响结构物的耐久性,严重的会使结构破坏倒塌,甚至造成人员伤亡和经济损失等。混杂纤维混凝土作为复合材料领域中颇有发展前景的一个新兴的分支,因其内部掺杂了两种或两种以上纤维,能有效改善混凝土内部孔隙结构,从不同层次上改善纤维三维分布的均衡性以及集料与纤维的协调作用,使之相互取长补短,产生复合效应,提高阻裂增韧性能。那么混杂纤维混凝土的抗硫酸盐侵蚀性能又是怎样呢?论文通过采用试验研究与理论分析相结合的方法,在深入分析混凝土受硫酸盐侵蚀机理和纤维对混凝土力学性能增强机理的基础上,对在混凝土中掺加玄武岩纤维和聚丙烯纤维的混杂纤维混凝土试件进行硫酸盐侵蚀快速试验。通过试验模拟与实际条件接近的干湿循环作用,根据混凝土受Na2SO4溶液侵蚀的特点,采用宏观和微观相结合的研究方法,宏观上观测表观现象、质量变化、相对动弹性模量变化、不同侵蚀龄期后强度(抗压强度和劈裂抗拉强度)变化等,微观上检测混杂纤维混凝土中不同龄期不同侵蚀深度处硫酸根离子浓度、孔隙率,并初步建立了混杂纤维混凝土的微-宏观损伤模型。结果表明：混杂纤维混凝土受硫酸盐侵蚀后其抗压强度、劈裂抗拉强度、质量变化、相对动弹性模量及同一侵蚀龄期和深度的硫酸根离子浓度等性能指标均优于普通混凝土。文中关于混杂纤维混凝土理论和试验研究的一系列研讨,对于提高纤维混凝土材料抗硫酸盐侵蚀性能具有理论意义和工程应用价值。
[Abstract]:The durability failure of concrete structures caused by environment is mainly manifested in corrosion of reinforcement and corrosion of concrete. The corrosion of concrete is divided into chemical corrosion, freeze-thaw damage and alkali aggregate reaction. Sulfate erosion is the most complex and harmful environmental erosion in chemical corrosion. After sulphate erosion, concrete appears as expansion, cracking, dissolution, exfoliation and decrease of strength, which will affect the durability of structure, cause structural damage and collapse, even cause casualties and economic losses. Hybrid fiber reinforced concrete is a promising branch in the field of composite materials, because it has two or more kinds of fibers in it, it can effectively improve the pore structure of concrete. The equilibrium of fiber three-dimensional distribution and the coordination of aggregate and fiber can be improved from different levels to make them complement each other and produce compound effects and improve the anti-cracking and toughening properties. What about the sulphate resistance of hybrid fiber reinforced concrete? Based on the experimental study and theoretical analysis, the mechanism of sulfate erosion of concrete and the mechanism of strengthening mechanical properties of concrete by fiber are analyzed in this paper. The sulphate erosion test of hybrid fiber reinforced concrete with basalt fiber and polypropylene fiber was carried out. According to the characteristics of concrete corroded by Na2SO4 solution, the effects of dry and wet circulation, which are close to the actual conditions, are simulated. The macroscopic and microscopic research methods are used to observe the changes of apparent phenomena, mass changes and relative dynamic elastic modulus of concrete. The change of strength (compressive strength and splitting tensile strength) after different erosion age, the concentration and porosity of sulfate ion in hybrid fiber reinforced concrete at different ages and different erosion depth were detected. The micro-macro damage model of hybrid fiber reinforced concrete was established. The results show that the compressive strength, splitting tensile strength, mass change, relative dynamic elastic modulus and sulfate ion concentration of the same erosion age and depth of hybrid fiber reinforced concrete are better than that of ordinary concrete. In this paper, a series of theoretical and experimental studies on hybrid fiber reinforced concrete are discussed, which are of theoretical significance and engineering application value for improving the sulfate corrosion resistance of fiber reinforced concrete materials.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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