压应力作用下混凝土中氯离子侵蚀性能研究

发布时间：2018-03-18 04:31

本文选题：桥梁工程　切入点：混凝土耐久性　出处：《中国公路学报》2017年04期 　论文类型：期刊论文

【摘要】：为系统研究氯盐环境中压应力作用下混凝土的耐久性,设计了1组预应力混凝土构件,分别施加0%、10%、25%、50%、75%、90%混凝土抗压强度设计值的压应力。通过测量不同压应力水平试件的动弹性模量,得出了不同压应力水平下混凝土损伤度的变化规律;同时对压应力作用下混凝土中的氯离子侵蚀试验结果进行横向对比,提出用应力影响系数来反映压应力对氯离子侵蚀速率的影响程度;然后通过不同水平压应力作用下混凝土的力学损伤和应力影响系数变化规律的比较分析,给出了实用、完整的应力影响系数三段式计算方法,并建立了基于损伤变量的应力影响系数表达式。结果表明:不同水平压应力作用下混凝土应力影响系数与以动弹性模量表征的损伤度变化曲线都为二次抛物线,存在相同的压应力临界值,对于普通混凝土,其值约为立方体抗压强度标准值的25%,从简考虑,对水灰比在0.35~0.55的混凝土可取10 MPa;压应力作用导致的力学损伤是改变混凝土中氯离子侵蚀性能的直接原因,不同水平压应力作用下,应力影响系数与以动弹性模量表征的损伤变量能同步变化。
[Abstract]:In order to systematically study the durability of concrete under compressive stress in chloride environment, a group of prestressed concrete members was designed. The compressive stress of the design value of the compressive strength of concrete is measured by measuring the dynamic elastic modulus of the specimens with different compressive stress levels, and the variation law of the damage degree of concrete under different compressive stress levels is obtained. At the same time, the results of chloride erosion test in concrete under compressive stress are compared horizontally, and the influence coefficient of stress is put forward to reflect the degree of influence of compressive stress on chloride erosion rate. Then, through the comparative analysis of the law of mechanical damage and stress influence coefficient of concrete under different horizontal compressive stress, a practical and complete three-stage calculation method of stress influence coefficient is given. The expression of stress influence coefficient based on damage variable is established. The results show that the stress influence coefficient of concrete under different horizontal compressive stress and the curve of damage degree represented by dynamic elastic modulus are both quadratic parabola. There is the same critical value of compressive stress. For ordinary concrete, the value is about 25 of the standard value of cubic compressive strength. For concrete with water-cement ratio of 0.35 to 0.55, the mechanical damage caused by compressive stress is the direct reason to change the corrosion performance of chloride ions in concrete. The stress influence coefficient can change synchronously with the damage variable characterized by dynamic elastic modulus.
【作者单位】：中南大学土木工程学院;湖南工程学院建筑工程学院;
【基金】：国家自然科学基金重点项目(U1361204)
【分类号】：TU528

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