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设计水灰比为0.55的素混凝土棱柱体试件,研究加载中和加载后不同压应力水平下的氯离子在混凝土内的侵蚀。对试件在8%浓度的氯化钠溶液中浸泡180 d后的取样进行测试,测试结果表明,当施加的压应力小于抗压强度的70%时,持续荷载与瞬时荷载下混凝土内同一深度的自由氯离子质量分数变化很小,且没有一定的规律性。而当压应力施加到95%的抗压强度后卸载时,混凝土内的氯离子质量分数明显增大。施加不大于70%抗压强度的压应力后,混凝土表观氯离子扩散系数有所减小,持续荷载下回归得到的表观氯离子扩散系数比相同应力水平下瞬时荷载时的要小,顺着荷载施加方向的氯离子质量分数和表观扩散系数要小于垂直荷载施加方向的值。根据试验数据及所需满足的边界条件建立了相应的计算公式。
A concrete plain concrete prism specimen with a water-cement ratio of 0.55 was designed to study the corrosion of chloride ions in concrete under different compressive stress levels after loading and loading. The test specimens were immersed in 8% NaCl solution for 180 days. The test results showed that when the compressive stress applied is less than 70% of the compressive strength, the continuous load and the same depth within the concrete under transient load Free chloride ion mass fraction change is small, and there is no certain regularity. When the compressive stress is applied to 95% of the compressive strength after unloading, the mass fraction of chloride ions in concrete significantly increased. The apparent chloride ion diffusion coefficient of concrete decreased after the compressive stress of not more than 70% compressive strength was applied, and the apparent chloride ion diffusion coefficient obtained under the continuous load was smaller than that under the same stress level The chloride ion mass fraction and apparent diffusion coefficient in the direction of load application are smaller than those in the vertical load application direction. According to the experimental data and the required boundary conditions, corresponding formulas are established.