荷载作用下粉煤灰混凝土硫酸盐腐蚀研究

Study on Sulfate Corrosion of Fly Ash Concrete under Stress Loading

通过试验模拟围岩复杂环境中混凝土在硫酸盐侵蚀和外界围岩压力作用下的侵蚀特点,分析不同侵蚀时间后混凝土抗压强度和动弹性模量经时变化规律,讨论溶液质量分数和应力水平对混凝土损伤规律的影响;根据SEM图片和XRD图谱,分析混凝土微结构的变化。试验结果表明:当试件受300 k N、质量分数5%硫酸盐溶液耦合作用时,其抗压强度和动弹性模量衰减率最大,分别为8.8%和20.4%。外界应力对混凝土结构的破坏作用及腐蚀产物钙矾石和石膏的膨胀作用在试件内部形成微裂纹,裂纹随侵蚀时间的增长而增多和扩展。

The experiment simulate the erosion characteristics of concrete under sulfate attack and surrounding rock pressure. The parameters are tested and analyzed, including concrete compressive strength and dynamic elastic modulus over erosion time. The test discuss the influence of solution concentration and stress level. According to SEM image and XRD atlas, the test analyze the change of microstructure of concrete. The test results show that when the sample is subjected to the coupling action of 300 kN and 5% concentration of sulfate solution, its compressive strength and dynamic modulus of attenuation rate are the biggest, and the attenuation rates are 8.8% and 20.4% respectively. Destruction of concrete structure by external stress and expansive of ettringite and gypsum cause micro cracks inside sample. With the erosion time increasing, the micro cracks increase and expand.