环境条件和应力水平对混凝土中氯离子传输的影响

Effects of environmental conditions and stress level on chloride ion transport in concrete

为了研究自然环境中混凝土的氯盐侵蚀过程,进行了不同侵蚀角度、氯化钠溶液质量浓度、环境温度、应力水平下的混凝土盐雾加速侵蚀试验,分别探讨了在不同的条件下氯离子在混凝土中的扩散规律.结果表明:盐雾箱中试件放置角度不同,其表面氯离子聚集量会不同,最终导致氯离子侵蚀程度不同,其中以平面或45°侧面为侵蚀面时,表面氯离子质量分数较高,氯离子侵蚀程度严重;随着氯化钠溶液质量浓度的增大,盐雾沉降量增加,表面氯离子质量分数也增加,不过最终会达到一个衡定值;随着环境温度的升高,氯离子表观扩散系数逐渐增大;由于压应力状态下混凝土内部结构更加密实,氯离子表观扩散系数显著减小.

To investigate the diffusion process of chloride ion in concrete under atmosphere environment, a series of tests were conducted under the conditions of different salt-fog spray angle, environment tem- perature, mass concentration of sodium chloride solution and compressive stress level. The results show that surface chloride ion mass fraction for specimens under different spray angles of salt-fog were different, which leads to a great change of diffusion degree of chloride ions in concrete. The surface chloride ion mass fraction is high when the angle of erosion surface is 0° or 45°, which causes severe erosion in concrete. The surface chloride ion mass fraction is increased with the increasing of mass concentration of sodium chloride solution until a stable value. The apparent diffusion coefficient of chloride ion is increased with the increasing of temperature, and decreased significantly with the increasing of compressive stress level due to the dense concrete by stress.