干湿循环下受硫酸钠侵蚀混凝土内钙钒石热分析研究  

Thermal Analysis of Ettringite in Concrete Attacked by Sodium Sulfate in Dry-wet Cyclic Environment

作　　者：陈记豪[1] 赵顺波[2] 姚继涛[1] 

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]华北水利水电学院土木与交通学院,河南郑州450011

出　　处：《应用基础与工程科学学报》2010年第6期950-958,共9页Journal of Basic Science and Engineering

基　　金：河南省杰出青年科学基金(04120002300);河南省外国专家局引进国外技术;管理人才重点项目(20094100099)

摘　　要：按照硫酸钠溶液浸泡15d/自然风干15d的循环制度进行了混凝土腐蚀试验,采用热分析技术对混凝土腐蚀产物进行了辨别和定量比较.试验表明:干湿循环与硫酸钠共同作用下,腐蚀龄期360d内的混凝土腐蚀产物以钙钒石为主,仅处于硫酸根离子浓度为50000mg/L的硫酸钠溶液中的混凝土表面在部分龄期检测到了石膏的生成.钙钒石的含量按混凝土试件由表及里依次递减,达到一定龄期时,第二层(距表面1.5—3.5mm)混凝土中钙钒石的含量大于第一层(距表面0—1.5mm).同一水灰比混凝土的相同层中钙钒石的含量随龄期增长而增多.混凝土中钙钒石的含量一般随硫酸根离子浓度的升高而增多,水灰比对混凝土中钙钒石含量的影响因硫酸根离子浓度而变化.硫酸根离子浓度为800mg/L和6000mg/L的硫酸钠溶液中,第一层混凝土中钙钒石的含量随水灰比增大而减小,第二层混凝土中钙钒石的含量随水灰比增大而增加,混凝土中钙钒石的总含量随水灰比增大而降低.硫酸根离子浓度为50000mg/L的硫酸钠溶液中,混凝土中钙钒石的总含量随水灰比增大而增多.The experiments were carried out according to the wet-dry cyclic regulation of steeping concrete in sodium sulfate solution for 15d and air-drying naturally for 15d.The erosion products of the concrete were distinguished and quantitatively compared by the thermal analysis.The results showed that the main erosion product was ettringite in 360d of erosion ages,the gypsum only detected in the surface of concrete immersed in sodium sulfate solution of higher SO4^2- concentration of 50000mg/L at some erosion ages.The content of ettringite in concrete decreased from the surface to the inside at first,and that in the second layer was over in the first layer at certain erosion age.Here,the depth of the first layer was 1.5mm from the surface of concrete,and the second layer was deep from 1.5mm to 3.5mm inside the surface of concrete.With the same water to cement ratio（W/C）,the ettringite content in the same layer of concrete increased with the increase of the erosion age.The content of ettringite was basically raised with the increase of SO4^2- concentration,the influence of W/C on the content of ettringite varied due to the change of SO4^2- concentration.When the concrete immersed in sodium sulfate solution with SO2-4 concentration of 800mg/L and 6000mg/L,with the increase of W/C,the content of ettringite in the first layer decreased,but that in the second layer increased,the total content of ettringite still decreased.Immersed in sodium sulfate solution with SO4^2- concentration of 50000mg/L,the total content of ettringite in concrete increased with the increase of W/C.

关 键 词：混凝土 硫酸钠 热分析 钙钒石 石膏 

分 类 号：TU528.572[建筑科学—建筑技术科学]