冻融循环作用下钢纤维混凝土的力学性能研究

发布时间：2018-10-24 08:18

【摘要】：在我国北方寒冷地区,由于气候变化所产生的正负温度交替现象,使冻融破坏成为混凝土结构物的主要病害之一,严重影响了混凝土结构的安全使用和长期运行。混凝土的抗冻性能是评价混凝土耐久性的重要指标之一,长期的冻融循环作用会导致混凝土的耐久性严重下降,进而混凝土的力学性能也将发生严重的衰退。而在混凝土中掺入适量钢纤维能有效改善混凝土的抗冻耐久性,并提高混凝土在冻融循环作用下的力学性能。随着我国国民经济的飞速发展,钢纤维混凝土的应用已经逐渐推广开来。因此,研究钢纤维混凝土的力学性能具有重要的实际意义。本文通过理论分析和试验研究,主要完成的工作内容如下:1、本文制作了钢纤维掺量分别为0、0.75%、1.5%的钢纤维混凝土试件,并对混凝土试件进行了冻融循环试验,分别进行了0次、50次、100次、150次和200次冻融循环,冻融循环每进行50次,测量一次混凝土试件的质量损失和动弹性模量,并绘制冻融循环次数与质量损失、相对动弹模量的变化曲线。结果表明,随着钢纤维掺量提高,混凝土抗剥蚀能力随之增强,钢纤维起到了增韧、阻裂的效果。2、进行冻融循环试验之后,对冻融作用后的钢纤维混凝土试件进行立方体抗压强度试验和棱柱体抗折强度试验,观察混凝土试件的破坏形态并记录试件的抗压强度、抗折强度数据,绘制不同钢纤维掺量的混凝土试件的抗压强度、抗折强度与冻融循环次数的关系曲线,分析钢纤维体积掺量及冻融循环次数对混凝土的力学性能的影响。结果表明,冻融初期,掺入钢纤维对混凝土抗压、抗折强度影响较大,但随着冻融循环次数增多,钢纤维对混凝土力学性能影响较小。3、通过以上试验结果和理论分析,研究钢纤维的掺入对混凝土抗冻耐久性的影响,并分析钢纤维混凝土的冻融破坏机理,建立了冻融损伤模型,为建立钢纤维混凝土的抗冻耐久性能指标提供理论依据。
[Abstract]:In the cold region of northern China, freeze-thaw damage has become one of the main diseases of concrete structures due to the positive and negative temperature alternation caused by climate change, which has seriously affected the safe use and long-term operation of concrete structures. The frost resistance of concrete is one of the important indexes to evaluate the durability of concrete. The long-term freeze-thaw cycle will lead to the serious decline of the durability of concrete and the deterioration of the mechanical properties of concrete. The addition of steel fiber in concrete can effectively improve the durability of concrete and improve the mechanical properties of concrete under the action of freeze-thaw cycle. With the rapid development of China's national economy, the application of steel fiber reinforced concrete (SFRC) has been gradually popularized. Therefore, it is of great practical significance to study the mechanical properties of steel fiber reinforced concrete (SFRC). Through theoretical analysis and experimental study, the main work accomplished in this paper is as follows: 1. The steel fiber concrete specimens with 0 0. 75% steel fiber content and 1.5% steel fiber content are made in this paper, and freeze-thaw cycle tests are carried out on concrete specimens. After 0, 50, 100, 150 and 200 freeze-thaw cycles were carried out respectively, the mass loss and dynamic elastic modulus of concrete specimens were measured for each 50 freeze-thaw cycles, and the number and loss of freeze-thaw cycles were plotted. The curve of relative dynamic modulus. The results show that with the increase of steel fiber content, the anti-denudation ability of concrete increases, and the steel fiber has the effect of toughening and cracking resistance. 2. After freeze-thaw cycle test, The cube compressive strength test and the prism flexural strength test were carried out on the steel fiber reinforced concrete specimens after freezing and thawing. The failure patterns of the concrete specimens were observed and the compressive strength and the flexural strength data of the specimens were recorded. The relationship curves of compressive strength, flexural strength and freeze-thaw cycle times of concrete specimens with different steel fiber content were drawn, and the effects of steel fiber volume content and freeze-thaw cycle times on the mechanical properties of concrete were analyzed. The results show that at the initial stage of freezing and thawing, the influence of steel fiber on the compressive strength and flexural strength of concrete is great, but with the increase of freeze-thaw cycle times, the influence of steel fiber on the mechanical properties of concrete is small. 3. Through the above experimental results and theoretical analysis, The influence of steel fiber on the durability of concrete is studied, and the mechanism of freeze-thaw damage of steel fiber concrete is analyzed. The damage model of freeze-thaw damage is established, which provides a theoretical basis for the establishment of durability index of steel fiber concrete.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.572

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