为研究西部盐渍土地区复杂环境下混凝土力学性能演变规律，通过自制加速腐蚀设备研究半浸泡在不同温度（20、40、60 ℃）、不同质量分数（0%、5%、10%）的硫酸钠溶液中混凝土表面产生的结晶程度以及轴心和分区抗压强度的变化规律。研究结果表明： 1）单硫酸盐侵蚀作用下混凝土出现结晶和轻微的混凝土剥落现象，其力学性能无明显衰减。2）单热疲劳作用对混凝土力学性能的影响不同，其中40 ℃热疲劳能提升混凝土的力学性能，而60 ℃热疲劳使力学性能显著衰减。3）热疲劳和硫酸盐侵蚀耦合作用下混凝土出现严重的结晶和剥落现象，力学性能大幅度衰减； 耦合作用下热疲劳使混凝土在侵蚀前期出现劣化，而硫酸盐作用在侵蚀后期开始与热疲劳发生耦合效应加速混凝土劣化。4）混凝土吸附区和浸泡区的力学性能变化趋势相同，但吸附区的衰减幅度比浸泡区大得多； 且通过回归分析发现分区的力学性能和整体性能之间存在较高的线性相关性，而吸附区的性能劣化是混凝土整体性能劣化的主要原因。
Herein, a self-made accelerated corrosion
equipment is used to analyze the crystallization degree, axial and zonal
compressive strength of concrete surface in different concentrations (0%, 5%,
and 10%) of sodium sulfate solution at different temperatures ( 20 ℃, 40 ℃, and 60 ℃),
revealing the effect of environmental thermal fatigue-sulfate
erosion coupling on the mechanical properties of concrete in western saline
soil areas in China. Findings are as follows: (1) Under the action of sulfate
erosion, the morphology of the specimen shows crystallization and slight
concrete spalling, but its mechanical properties exhibit no obvious
attenuation. (2) The effect of thermal fatigue on the mechanical properties of
concrete varies. The thermal fatigue at 40 ℃ improves
the mechanical properties of the specimens, while the thermal fatigue at 60 ℃ significantly reduces the mechanical properties. (3) Under the
coupling effect of thermal fatigue and sulfate erosion, the morphology of the
specimens shows serious damages, such as serious crystallization and concrete
spalling, and the mechanical properties also shows a significant attenuation.
Under the coupling effect, the thermal fatigue causes the deterioration of the
concrete from the early stage of the erosion, while the sulfate effect begins
to accelerate the deterioration of the concrete in the late stage of the
erosion. (4) Comparing the mechanical properties of the concrete adsorption
zone and the immersion zone, it is found that although the two trends are the
same, the attenuation of the adsorption zone is larger than that of the
immersion zone. Regression analysis shows that the mechanical properties of
partial concrete is highly correlated with overall concrete, and the deterioration
of the concrete at the adsorption zone primarily causes the overall concrete
deterioration.
