有机酸对红黏土置换水泥土桩的腐蚀性试验研究
发布时间：2018-10-29 13:00
【摘要】：地下水土环境可能对地下结构产生腐蚀,导致其强度降低,最终危及整个建(构)筑物的安全,研究各种地下水土环境对地下结构的影响有非常重要理论和实际价值。论文以红黏土水泥土复合体为研究对象,通过强度试验和浸泡试验分别探讨了：红黏土水泥土复合体无侧限抗压强度与水泥掺入比、龄期的关系和有机酸(柠檬酸、富里酸、水杨酸、草酸)与红黏土水泥土复合体的相互作用机理。主要做了以下研究工作： (1)红黏土水泥土复合体的无侧限抗压强度可达2MPa以上,其强度对水泥掺入比的敏感度随掺入比的提高而降低；前期强度与90天强度的比值随水泥掺入比的增加而减小,用前期强度估算90天强度时,应考虑掺入比的影响。 (2)柠檬酸对红黏土水泥土复合体具有强烈的腐蚀性,其侵蚀过程可分为耗酸速率快速下降、稳定、波动变化三个阶段；pH值大于4.5时,其侵蚀以分解溶蚀作用为主；pH值小于3.5时,以结晶膨胀作用为主；pH值在3.5与4.5之间时,两种作用共存,其中表层以分解溶蚀作用为主,内部以结晶膨胀作用为主；在此基础上建立了柠檬酸侵蚀红黏土水泥土复合体的腐蚀预测模型。 (3)富里酸对养护3天的红黏土水泥土复合体具有一定腐蚀性,对养护37天的红黏土水泥土复合体的腐蚀性较弱,其侵蚀过程可分为快速反应和缓慢反应两个阶段,其中以第一阶段的侵蚀为主,第二阶段侵蚀作用较弱。 (4)水杨酸对红黏土水泥土复合体具有较强的腐蚀性,pH值越小腐蚀性越强,其侵蚀主要以对水泥水化产物的分解溶蚀为主；整个侵蚀过程可分为耗酸速率快速下降和稳定两个阶段；模型f(t)=atb能很好的描述不同pH值对应的耗酸量随时间的变化关系。 (5)草酸对红黏土水泥土复合体的侵蚀过程为一个分解和重结晶过程,红黏土水泥土复合体中水泥水化产物和三氧化二铁被分解,重结晶生成难容的草酸钙(CaC204)和草酸亚铁(FeC204)；整个侵蚀过程可分为三个阶段：结晶层形成阶段,过渡阶段,快速反应阶段,前两阶段主要以对水泥水化产物的分解转化为主,第三阶段既存在对水泥水化产物的分解转化,也存在对红黏土中氧化铁的分解转化。 (6)有机酸对红黏土水泥土复合体的侵蚀过程不仅与溶液pH值有关,溶液中有机酸种类也是一个决定性的因素,有机酸种类不同侵蚀机理也存在差异,最终产生的破坏作用也不相同。
[Abstract]:The underground soil and water environment may corrode the underground structure, resulting in its strength decreasing, and finally endangering the safety of the whole building. It is of great theoretical and practical value to study the influence of various underground soil and water environment on the underground structure. This paper takes the red clay cement-soil complex as the research object, through strength test and soaking test, discusses the relationship between the unconfined compressive strength of the red clay cement-soil complex and the ratio of cement to cement, age and organic acid (citric acid, fulvic acid, citric acid, fulvic acid). The interaction mechanism between salicylic acid (oxalic acid) and red clay cement-soil complex. The main work is as follows: (1) the unconfined compressive strength of red clay cement-soil complex can reach 2MPa, and the sensitivity of strength to cement blending ratio decreases with the increase of cement ratio; The ratio of pre-strength to 90-day strength decreases with the increase of cement blending ratio. (2) citric acid has a strong corrosive effect on the cement-soil complex of red clay, and the erosion process can be divided into three stages: the acid consumption rate decreases rapidly, the acid consumption rate is stable and fluctuates, and when the pH value is greater than 4. 5, the corrosion process is dominated by decomposition and dissolution. When the pH value is less than 3. 5, the effect of crystallization expansion is dominant, and when the pH value is between 3. 5 and 4. 5, the two interactions coexist, in which the surface layer is mainly composed of decomposition and dissolution, and the inner layer is dominated by crystallization expansion. On this basis, the corrosion prediction model of citric acid erosion red clay cement soil complex is established. (3) Furic acid is corrosive to the red clay cement-soil complex for 3 days, and weak to the red clay cement soil complex for 37 days. The erosion process can be divided into two stages: quick reaction and slow reaction. Among them, the first stage of erosion is the main, the second stage of erosion is weak. (4) salicylic acid has strong corrosiveness to the cement soil complex of red clay, the smaller the pH value is, the stronger the corrosion is, and the main erosion is the decomposition and dissolution of cement hydration products; The whole process of erosion can be divided into two stages: the fast decreasing of acid consumption rate and the stable stage, and the model f (t) = atb can well describe the relationship between the acid consumption and the time of different pH values. (5) the erosion process of oxalic acid to red clay cement soil complex is a process of decomposition and recrystallization, and the hydration products of cement and iron trioxide in red clay cement soil complex are decomposed. Recrystallization produces intolerable calcium oxalate (CaC204) and ferrous oxalate (FeC204). The whole process of erosion can be divided into three stages: crystalline layer formation stage, transition stage, rapid reaction stage, the first two stages are mainly to decompose the hydration products of cement into the main, the third stage is the decomposition and transformation of cement hydration products. There is also the decomposition and transformation of iron oxide in red clay. (6) the erosion process of organic acid to cement-soil complex of red clay is related not only to the pH value of solution, but also to the type of organic acid in solution, and the erosion mechanism of organic acid is also different. The ultimate destructive effect is also different.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1
本文编号：2297766
[Abstract]:The underground soil and water environment may corrode the underground structure, resulting in its strength decreasing, and finally endangering the safety of the whole building. It is of great theoretical and practical value to study the influence of various underground soil and water environment on the underground structure. This paper takes the red clay cement-soil complex as the research object, through strength test and soaking test, discusses the relationship between the unconfined compressive strength of the red clay cement-soil complex and the ratio of cement to cement, age and organic acid (citric acid, fulvic acid, citric acid, fulvic acid). The interaction mechanism between salicylic acid (oxalic acid) and red clay cement-soil complex. The main work is as follows: (1) the unconfined compressive strength of red clay cement-soil complex can reach 2MPa, and the sensitivity of strength to cement blending ratio decreases with the increase of cement ratio; The ratio of pre-strength to 90-day strength decreases with the increase of cement blending ratio. (2) citric acid has a strong corrosive effect on the cement-soil complex of red clay, and the erosion process can be divided into three stages: the acid consumption rate decreases rapidly, the acid consumption rate is stable and fluctuates, and when the pH value is greater than 4. 5, the corrosion process is dominated by decomposition and dissolution. When the pH value is less than 3. 5, the effect of crystallization expansion is dominant, and when the pH value is between 3. 5 and 4. 5, the two interactions coexist, in which the surface layer is mainly composed of decomposition and dissolution, and the inner layer is dominated by crystallization expansion. On this basis, the corrosion prediction model of citric acid erosion red clay cement soil complex is established. (3) Furic acid is corrosive to the red clay cement-soil complex for 3 days, and weak to the red clay cement soil complex for 37 days. The erosion process can be divided into two stages: quick reaction and slow reaction. Among them, the first stage of erosion is the main, the second stage of erosion is weak. (4) salicylic acid has strong corrosiveness to the cement soil complex of red clay, the smaller the pH value is, the stronger the corrosion is, and the main erosion is the decomposition and dissolution of cement hydration products; The whole process of erosion can be divided into two stages: the fast decreasing of acid consumption rate and the stable stage, and the model f (t) = atb can well describe the relationship between the acid consumption and the time of different pH values. (5) the erosion process of oxalic acid to red clay cement soil complex is a process of decomposition and recrystallization, and the hydration products of cement and iron trioxide in red clay cement soil complex are decomposed. Recrystallization produces intolerable calcium oxalate (CaC204) and ferrous oxalate (FeC204). The whole process of erosion can be divided into three stages: crystalline layer formation stage, transition stage, rapid reaction stage, the first two stages are mainly to decompose the hydration products of cement into the main, the third stage is the decomposition and transformation of cement hydration products. There is also the decomposition and transformation of iron oxide in red clay. (6) the erosion process of organic acid to cement-soil complex of red clay is related not only to the pH value of solution, but also to the type of organic acid in solution, and the erosion mechanism of organic acid is also different. The ultimate destructive effect is also different.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1
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