| 摘要: |
| 为了揭示不同腐蚀环境下混凝土的软化特性，分别开展了三种环境下(清水、Na2SO4、Na2SO4+NaCl)混凝土I型断裂性能试验，计算分析粘聚韧度实测值及不同形式下的解析值，并确定各龄期的软化曲线。结果表明：三种环境中混凝土的粘聚韧度基本呈先增后减趋势，龄期达到270 d后明显下降且速率接近，360 d时，清水、Na2SO4环境中粘聚韧度、临界裂尖张开位移分别取最大、最小值，Na2SO4+NaCl环境的取值居中，说明长期腐蚀导致混凝土的劣化，氯盐的加入有助于延缓硫酸盐对混凝土的侵蚀作用；Xu和Reinhardt修正的双线性软化曲线能够较好描述三种环境下混凝土的软化特性，清水、Na2SO4、Na2SO4+NaCl环境中λ分别取7、10、8时，粘聚韧度实测值与解析值最接近，反映了混凝土断裂过程区上内聚力的分布规律，根据Petersson 软化曲线所得粘聚韧度解析值较大；两种腐蚀环境中λ取值随龄期的增加整体呈减小趋势，Na2SO4环境中λ集中在6~10，Na2SO4+NaCl环境中λ集中在8~10。 |
| 关键词: 腐蚀环境 混凝土 断裂试验 双线性软化曲线 粘聚韧度 |
| DOI： |
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| 基金项目:国家自然科学基金(52101313, 52171270, 51879168, 12202179)；国家自然科学基金委–河南省联合基金重点项目(U23A20672)；江苏省自然科学基金面上项目(BK20221400)；南京工程学院科研启动基金(YKJ202322) |
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| Cohesive toughness and softening curve of concrete under different corrosive environments |
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Gong Nina1, Li Shuang2, Fan Xiangqian3, Wang Zheyuan2, Geng Fangfang4, Zhang Peng1, Li Qiankun2
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1.Institute of Civil Engineering and Intelligent Management,Nanjing Institute of Technology;2.College of Civil,Harbor and Coastal Engineering,Jiangsu Ocean University;3.Nanjing Hydraulic Research Institute;4.School of Architecture Engineering,Nanjing Institute of Technology
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| Abstract: |
| Abstract: In order to reveal the softening characteristics of concrete under different corrosive environments, mode-I fracture performance tests were conducted on concrete under three different environments (water, Na2SO4, Na2SO4+NaCl), calculating and analyzing the measured values of cohesive toughness and analytical values under different forms，and determining the softening curves at different ages. The results showed that the cohesive toughness of concrete in the three environments showed a trend of first increasing and then decreasing, with a significant decrease and a similar rate after reaching 270 days of age. At 360 days, the cohesive toughness and the critical crack opening displacement in the water and Na2SO4 environments reached their maximum and minimum values, respectively, while the values in Na2SO4+NaCl environment were in the middle, indicating that long-term corrosion led to the deterioration of concrete, and the addition of chloride salts helped to delay the erosion of sulfate on concrete. The bilinear softening constitutive curve modified by Xu and Reinhardt can better describe the softening characteristics of concrete in three different environments. When the values of λ were taken as 7, 10, and 8 in water, Na2SO4, and Na2SO4+NaCl environments, respectively, the measured and analytical values of cohesive toughness were closest, reflecting the distribution law of cohesive force in the fracture process zone of concrete. The analytical values of cohesive toughness obtained from Petersson softening curve were relatively large. The values of λ in two corrosive environments showed an overall decreasing trend with increasing age, with λ concentrating between 6~10 in Na2SO4 environment and 8~10 in Na2SO4+NaCl environment. |
| Key words: Corrosive environments Concrete Fracture test Bilinear softening curve Cohesive toughness |
