化学溶液长期浸泡作用下灰岩溶蚀劣化研究

Study on the Corrosion and Deterioration of Limestone under Long-Term Immersion of Chemical Solution

在酸性(pH=3)、中性(pH=7)、碱性(pH=11)3种溶液环境中开展了灰岩浸泡溶蚀试验,测试了不同浸泡周期灰岩的单轴抗压强度、表面微观形貌、浸泡溶液的pH值及Ca^(2+)浓度,并讨论了灰岩宏观力学性能的劣化机制。研究表明:灰岩在酸性环境中溶蚀劣化程度最大,中性环境次之,碱性环境最小;在试验初期,3种化学溶液的pH值均变化剧烈,并逐渐向中性转化,最终呈弱碱性;在酸性溶液中试验初期Ca^(2+)溶出速率较快;而在中性和碱性环境下则溶蚀反应缓慢;随着浸泡时间的增加,溶蚀灰岩在微观形貌上表现为微孔洞扩展,表面粗糙程度加剧;从溶蚀后灰岩微观损伤区域的统计结果来看,3种溶液环境下灰岩的单轴抗压强度均随损伤区域比的增加而减小,酸性环境中的损伤区域比最大,中性环境次之,碱性环境最小。

Limestone immersion corrosion test was carried out in acid(pH=3),neutral(pH=7)and alkaline(pH=11)solution environments.The uniaxial compressive strength,the micro morphology of dissolved limestone surface,the pH values and Ca^(2+) concentration of immersion solution were tested to discuss the deterioration mechanism of limestone.The results showed that the dissolution deterioration degree of limestone was the largest in acidic environment,followed by neutral environment and the smallest in alkaline environment.At the beginning of the test,the pH values of the three chemical solutions changed sharply,then gradually turned to neutral,and finally became weak alkaline.In the acid solution,the dissolution rate of Ca^(2+) was faster in the initial stage.In neutral and alkaline environment,the dissolution reaction was slow.With the increase of immersion time,the micro morphology of dissolved limestone showed the expansion of micro pores and the aggravation of surface roughness.According to the statistical results of micro damage area of limestone after dissolution,the uniaxial compressive strength of limestone decreased with the increase of damage area ratio in the three immersion solutions.The damage area ratio was the largest in acid environment,followed by neutral environment and the smallest in alkaline environment.