硫酸盐侵蚀与冻融循环共同作用下混凝土耐久性试验研究

发布时间：2018-05-14 03:14

本文选题：混凝土 + 冻融循环　；参考：《西安建筑科技大学》2013年硕士论文

【摘要】：我国北方寒冷地区水、土壤中含有丰富的硫酸盐。混凝土在遭受硫酸盐侵蚀与冻融循环共同作用时，较单一因素作用会产生更严重的破坏，影响混凝土结构的耐久性。因此开展硫酸盐侵蚀与冻融循环共同作用下混凝土耐久性研究有着重要的理论与工程实际意义。采用快速冻融试验方法，进行了普通混凝土盐冻（硫酸盐）试验，以硫酸盐溶液浓度、种类及冻融循环次数为主要考察因素，，分析了盐冻循环下混凝土外观、微观、质量、相对动弹性模量、抗压强度和损伤层厚度的变化规律；基于宏观损伤力学理论，建立了普通混凝土在盐冻循环下的损伤演化方程，探讨了随冻融循环次数的变化混凝土损伤演变规律。结果表明：硫酸盐溶液对混凝土冻融破坏既存在抑制作用又存在促进作用；随着冻融循环次数的增加，硫酸盐溶液对混凝土冻融破坏由抑制作用逐渐转变为促进作用；随着溶液浓度的增加，硫酸钠溶液对混凝土的冻融破坏由促进作用逐渐转变为抑制作用。开展了水冻和盐冻（5%硫酸钠）作用下普通混凝土受压应力-应变全曲线试验研究。对普通混凝土棱柱体进行快速冻融循环后，进行单轴抗压试验。得到了水冻和盐冻作用下普通混凝土应力-应变全曲线方程及相关参数。结果表明：随着冻融循环次数的增加，混凝土受压应力-应变全曲线逐渐趋于扁平，峰值应力、弹性模量不断下降，峰值应变不断增加。水冻作用下混凝土峰值应力、峰值应变和弹性模量初期变化较快，盐冻（5%硫酸钠）作用下后期变化较快。
[Abstract]:In the cold area of northern China, the soil is rich in sulfate. When the concrete is subjected to sulfate erosion and freeze-thaw cycle, it will cause more serious damage than the single factor, and affect the durability of concrete structure. Therefore, it is of great theoretical and engineering significance to study the durability of concrete under the combined action of sulfate erosion and freeze-thaw cycle. By using the method of rapid freeze-thaw test, the salt freezing (sulfate) test of ordinary concrete was carried out. With the concentration of sulfate solution, type and times of freeze-thaw cycle as the main factors, the appearance, microcosmic and quality of concrete under salt freezing cycle were analyzed. Based on the macroscopic damage mechanics theory, the damage evolution equation of ordinary concrete under salt freezing cycle is established. The damage evolution law of concrete with the number of freeze-thaw cycles is discussed. The results show that sulfate solution can inhibit and promote the freeze-thaw failure of concrete, and with the increase of freeze-thaw cycle times, the freezing and thawing failure of concrete is gradually changed from inhibiting effect to promoting effect by sulfate solution. With the increase of solution concentration, the freezing and thawing failure of concrete caused by sodium sulfate gradually changed from promoting effect to inhibiting effect. An experimental study on the stress-strain curve of ordinary concrete under the action of water freezing and salt freezing (5% sodium sulfate) was carried out. After rapid freeze-thaw cycle of common concrete prism, uniaxial compression test was carried out. The whole stress-strain curve equation and related parameters of ordinary concrete under the action of water freezing and salt freezing are obtained. The results show that with the increase of freeze-thaw cycles, the compressive stress-strain curve of concrete tends to flatten, the peak stress and elastic modulus decrease, and the peak strain increases. The peak stress, the peak strain and the elastic modulus of concrete changed rapidly at the initial stage under the action of water freezing, and the change was faster in the later stage under the action of salt freezing (5% sodium sulfate).
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528.0

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