| 摘要: |
| 为研究混凝土结构荷载与环境耦合作用下的混凝土性能劣化时变规律，对不同应力比的轴压荷载与不同浓度的硫酸钠溶液直接耦合作用下的混凝土强度劣化和微观机理进行了研究，轴压应力比取0%，15%，30%和45%，硫酸钠溶液浓度（质量分数，下同）取0%，5%和10%.结果表明：45%应力比的轴压荷载与硫酸钠溶液耦合对混凝土强度的劣化有显著促进作用；30%及以下应力比的轴压荷载与硫酸钠溶液耦合对混凝土强度的劣化有一定抑制作用，其中30%应力比的轴压荷载抑制作用最为显著；相比5%浓度的硫酸钠溶液，10%浓度的硫酸钠溶液对混凝土的劣化有显著加速作用.微观机理研究表明：轴压荷载与硫酸钠溶液耦合作用下，30%应力比作用下混凝土试件的界面过渡区劣化最轻，15%应力比作用下混凝土试件的界面过渡区损伤稍大于30%应力比作用下，45%应力比作用下混凝土试件的界面过渡区损伤劣化最严重；耦合作用下，微裂缝处的钙矾石和石膏等物质对界面过渡区的填充密实作用较小；随着侵蚀龄期的增加，界面过渡区微裂缝的劣化逐渐加重；在高应力比的轴压荷载与硫酸钠溶液耦合作用下，界面过渡区的劣化对混凝土性能影响更显著；在低应力比的轴压荷载与硫酸钠溶液耦合作用下，界面过渡区的劣化对混凝土性能影响不明显. |
| 关键词: 混凝土 轴压荷载 硫酸盐侵蚀 强度劣化 界面过渡区 微观分析 |
| DOI：103969/j.issn.1007 9629201803004 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目(51479174)；水沙科学与水利水电工程国家重点实验室开放基金资助项目(sklhse 2017 C 01) |
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| Strength Deterioration Mechanism of Concrete under Combined Action of Axial Compression and Sulfate Attack |
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LU Jingzhou, TIAN Lizong, TONG Liqiang, LIU Ying, ZHU Kongfeng
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School of Civil Engineering, Yantai University, Yantai 264005, China
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| Abstract: |
| The interaction effect of the simultaneous sustained stress and sulfate attack on the deterioration of concrete was experimentally investigated. The concrete cube specimens were loaded in axial compressive stress by creep apparatus and immersed in sodium sulfate solutions of concentrations of 0%, 5% and 10%(by mass）, and in tap water. The axial compression stresses ratios were as follows:0%, 15%, 30% and 45%. Test results show that, the combined action of the stress ratio of 45% with sulfate attack significantly accelerates the deterioration of concrete, and the compressive strength of concrete shows a downward trend with the increase of corrosion time. The axial compression at stress ratio of 30% or less and sulfate attack have inhibitory effect on the degradation of concrete strength. And the inhibitory effect under the stress ratio of 30% is more significant than that under the stress ratio of 15%. Compared with 5% concentration of sodium sulfate solution, 10% concentration of sodium sulfate solution has a significant acceleration effect on the deterioration of concrete. Microcosmic mechanism research shows that, under the real time combined action of axial compression and sulfate attack, the degradation of interface transition zone(ITZ) under the stress ratio of 30% is the least notable, the degradation of ITZ under the stress ratio of 15% is slightly greater, and the degradation of ITZ under the stress ratio of 45% is the most serious. During the combined erosion process, the filling effect of ettringite and gypsum in micro cracks is small. With the increase of corrosion age, the deterioration of micro cracks in the ITZ is gradually increased. Under combined action of the axial compression of high stress ratio and sulfate attack, the deterioration of ITZ has a more significant influence on concrete performance. Under combined action of the axial compression of low stress ratio and sulfate attack, the deterioration of ITZ has no notable influence on concrete performance. |
| Key words: concrete axial compression load sulfate attack strength degradation interfacial transition zone(ITZ) microanalysis |
