草酸侵蚀红黏土水泥土复合体的试验研究

Experimental on Erosion Mechanism of Oxalic Acid to Red Clay-cemented Soil

采用p H值为2.5,3.5和4.0的草酸溶液,对红黏土水泥土复合体试样进行了长期浸泡(200 d),通过观测浸泡过程中,试样外观和耗酸量随时间的变化,分析了草酸对红黏土水泥土复合体的腐蚀和作用机理。结果表明:草酸对红黏土水泥土复合体的侵蚀为一个分解和重结晶过程,复合体中水泥水化产物和Fe2O3被分解,重结晶生成难溶的草酸钙(Ca C2O4)和草酸亚铁(Fe C2O4),最终使红黏土水泥土复合体中的骨架连接物由水泥水化产物转换为草酸钙和草酸亚铁。

Long-term immersion(200 d) test of red clay-cemented soil composite was carried out in oxalic acid aqueous solutions with p H value of 2.5, 3.5 and 4.0. Through monitoring the changes of acid consumption and the variation of appearance of the test composite with time to reveal the corrosion behavior and the relevant mechanism of red clay- cemented soil composite in the oxalic acid. Results shows that the corrosion of the composite in the oxalic acid is a process related closely with sub-processes of decomposition and recrystallization, i.e. the hydration products of cement and Fe2O3 in the red clay-cemented soil composite are decomposed and then recrystallized into indissolvable Ca C2O4 and Fe C2O4, and finally the skeleton like connectors of the red clay- cemented soil were transformed into other products such as calcium oxalate and ferrous oxalate.