电化学除氯对钢筋腐蚀状态及其周围混凝土微观结构的影响  

Effect of Electrochemically Chlorine Extraction on the Corrosion State of Steel Bars and the Microstructure of Surrounding Concrete

作　　者：陈文龙 周旭东 张宇 张云升 马智聪 CHEN Wenlong;ZHOU Xudong;ZHANG Yu;ZHANG Yunsheng;MA Zhicong(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Guangdong Highway Construction Co.,Ltd.,Guangzhou 510000,China)

机构地区：[1]兰州理工大学土木工程学院,兰州730050 [2]广东省公路建设有限公司,广州510000

出　　处：《材料导报》2024年第23期68-75,共8页Materials Reports

基　　金：国家自然科学基金(52208249,U21A20150,52208292);甘肃省青年科学基金(22JR5RA288);甘肃省高等学校自然科学创新基金(2022CYZC-25);甘肃省绿色智慧公路关键技术示范项目(21ZD3GA002);公路混凝土桥梁耐久性关键技术,高性能土木工程材料国家重点实验室(2022CEM009)。

摘　　要：本工作分别采用1 A/m^(2)、2 A/m^(2)和3 A/m^(2)的电流密度对不同水灰比(0.47、0.38、0.33)掺盐混凝土进行30 d电化学除氯(ECE)修复,以钢筋腐蚀状态、除氯效率及残余氯离子浓度分布为指标,评价ECE修复效果,并结合扫描电镜(SEM)、X射线衍射(XRD)及核磁共振(NMR)测试方法,探究ECE处理前后混凝土水化产物、孔结构演变规律。结果表明:ECE处理可以阻止钢筋锈蚀或恢复钝化;水灰比增大、电流密度增加,ECE效率显著提升;ECE处理后,混凝土中Ca(OH)2含量增加,且Ca(OH)2晶体能有效填充孔隙,使靠近阳极处的混凝土密实度增大、孔隙率降低,而靠近阴极处混凝土中的水化产物被迫分解造成孔隙疏松。ECE处理后阴极处混凝土内微孔(0.001~0.1μm)向介孔(0.1~1μm)演变,对钢筋-混凝土粘结性能产生不利影响。In this work,using the current densities of 1 A/m^(2),2 A/m^(2)and 3 A/m^(2)to carry out electrochemical chlorine extraction(ECE)treatment for 30 days on concrete with different water-cement ratios(0.47,0.38,0.33),the corrosion state of steel bars,chlorine extraction efficiency and residual chloride concentration distribution were obtained to evaluate the effect of ECE treatment.Througth scanning electron microscopy,X-ray diffraction and nuclear magnetic resonance test methods,explored the evolution rule of concrete hydration products and pore structure before and after ECE treatment.The results show that ECE treatment can prevent steel corrosion or restore passivation.The increase of the water-cement ratio and the current density would significantly increase the chlorine extraction efficiency of ECE.After ECE treatment,the content of Ca(OH)2 in concrete increased,and Ca(OH)2 crystals could fill the pores,so that the density of concrete near the anode increased and the porosity reduced,while the hydration products in concrete near the cathode were decomposed,resulting in porosity.After ECE treatment,the micropores(0.001—0.1μm)in the concrete at the cathode evolved into mesopores(0.1—1μm),which was unfavorable to the bond performance of steel-concrete.

关 键 词：电化学除氯 钢筋混凝土 氯离子浓度分布 核磁共振 线性极化法 

分 类 号：TU528[建筑科学—建筑技术科学]