盐渍土通电环境中钢筋混凝土损伤劣化及尺寸效应试验研究  

Research on Damage Deterioration and Size Effect of Reinforced Concrete in Saline Soil Powered-on Environment

作　　者：路承功 魏智强[2] 乔宏霞[1,3] 曹辉[1] 乔国斌 LU Chenggong;WEI Zhiqiang;QIAO Hongxia;CAO Hui;QIAO Guobin(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;School of Science,Lanzhou University of Technology,Lanzhou 730050,China;Western Center of Disaster Mitigation in Civil Engineering of Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学土木工程学院,兰州730050 [2]兰州理工大学理学院,兰州730050 [3]兰州理工大学,西部土木工程防灾减灾教育部工程研究中心,兰州730050

出　　处：《材料导报》2021年第16期16042-16049,共8页Materials Reports

基　　金：国家自然科学基金(51168031,51868044)。

摘　　要：针对西部盐渍土地区混凝土结构在电流与腐蚀离子综合作用下耐久性突出问题,设计了室内恒电流通电加速试验,同时考虑试件尺寸效应的影响,将100 mm×100 mm×100 mm立方体及100 mm×100 mm×400 mm棱柱体试件置于盐渍土中进行耐久性试验,采用电化学方法进行腐蚀监测,利用裂缝观测仪密切关注裂缝开展情况,腐蚀结束后分别对混凝土及钢筋进行电镜扫描。研究结果表明:在盐渍土通电加速环境下,钢筋混凝土经历了失钝、自由膨胀、应力增长、裂缝开展四个阶段。钢筋表面有层片状、团簇状、颗粒状的疏松结构生成,锈蚀产物呈黑色、褐色,混凝土内有针杆状、冰溜状、薯条状晶体生长,裂缝沿钢筋周围纵向开展、分布。立方体试件腐蚀电位、腐蚀电流密度、裂缝开展宽度等指标均显著高于棱柱体试件,且立方体试件实际腐蚀效率是棱柱体试件的1.5~1.6倍。钢筋混凝土试件尺寸效应显著,强度等级越高,尺寸效应越明显,且对于普通强度等级钢筋混凝土,尺寸效应对其耐久性影响程度高于强度等级。Aiming at the prominent durability problem of concrete structures in western saline soil area under the combined action of current and corrosion ion,the constant current electrified acceleration test was designed.At the same time,considering the influence of specimen size,the 100 mm×100 mm×100 mm cube and 100 mm×100 mm×400 mm prismatic specimens were placed in saline soil for durability test.Electrochemical method was adopted for corrosion monitoring.Crack observation instrument was used to pay close attention to the development of cracks.After the end of corrosion,the concrete and steel were respectively scanned by electron microscopy.The results show that,under the condition of saline soil electrified acceleration,the reinforced concrete has gone through four stages:dulling,free expansion,stress growth and crack development.There are laminar,cluster and granular loose structures on the surface of the steel bar,and the corrosion products are black and brown.There are needle rod shaped,ice like and chip shaped crystals in the concrete,and the cracks are developed and distributed along the longitudinal direction around the steel bar.The corrosion potential,corrosion current density and crack development width of cube specimens are significantly higher than those of prism specimens,and the actual corrosion efficiency of cube specimens is 1.5—1.6 times of prism specimens.The size effect of reinforced concrete specimens is significant,the higher the strength level,the more obvious the size effect.The effect of size effect on its durability is higher than the strength level for the ordinary strength grade reinforced concrete.

关 键 词：钢筋混凝土 盐渍土 通电加速 尺寸效应 损伤劣化 

分 类 号：TU528[建筑科学—建筑技术科学]