摘要
根据兰州地铁沿线站台地下水和土壤中所含腐蚀离子配置含有SO^(4)_^(2-)、Cl^(-)、Mg^(2+)的4种复合盐溶液,将钢筋混凝土试件置于复合盐溶液中,每隔90 d通过电化学工作站及超声声速检测仪进行无损检测,利用非单调Wiener随机退化过程,以相对动弹性模量值达到0.4时作为混凝土失效破坏条件,以混凝土裂缝开展宽度达到0.2 mm时的腐蚀电流密度作为混凝土中钢筋的失效阈值,进而建立钢筋混凝土耐久性寿命预测模型.研究结果表明:复合盐溶液环境下,极化曲线整体向腐蚀电流密度增大和负电位方向移动,交流阻抗图谱呈现双容抗弧,初始时刻低频区阻抗弧半径大,斜率高,腐蚀周期增加,低频阻抗弧半径逐渐减小并向阻抗实部收缩,阻抗谱逐渐左移.裂缝宽度到达0.2 mm时腐蚀电流密度的失效阈值为7.6375μA/cm^(2),基于Wiener随机过程模型可以很好地反映钢筋混凝土在腐蚀环境中耐久性寿命变化.钢筋和混凝土寿命曲线均呈现出三阶段变化特点,钢筋寿命曲线第一阶段持续时间更长,第二阶段加速退化速率更快.通过Wiener随机过程得到钢筋的寿命小于混凝土寿命,在A、B、C、D四种溶液中的寿命分别约为7200 d、2900 d、4500 d及2000 d,而混凝土在4种溶液中的寿命分别约为10000 d、6500 d、5500 d及5000 d.且钢筋寿命对氯盐的敏感性大,而混凝土寿命对硫酸盐的敏感性大.
According to the corrosion ions in the groundwater and soil of the platforms along Lanzhou metro,four kinds of compound salt solutions containing SO^(4)_^(2-),Cl^(-),and Mg^(2+)were prepared.The reinforced concrete specimens were placed in the compound salt solution,and nondestructive testing was conducted every 90 days by an electrochemical workstation and ultrasonic sound velocity detector.A durability life prediction model of reinforced concrete was established by using a non-monotone Wiener stochastic degradation process.When the relative dynamic modulus of elasticity reached 0.4,it was regarded as the failure condition of concrete,and when the crack width reached 0.2 mm,the corrosion current density was used as the failure threshold of reinforcement in concrete.The results show that,under the coupled salt solution environment,the polarization curve moves towards the direction of increasing corrosion current density and negative potential.The ac impedance spectrum shows a double capacitive reactance arc.At the initial moment,the low-frequency impedance arc radius is large,the slope is high,and the corrosion cycle increases.The low-frequency impedance arc radius gradually decreases and shrinks to the real part of the impedance,and the impedance spectrum gradually shifts to the left.When corrosive ions enter the concrete,cementitious materials are consumed,and expansion products are produced.When the crack width reaches 0.2 mm,the failure threshold of the corrosion current density is 7.6375μA/cm^(2).The life of steel bars is less than that of concrete through Wiener random process.The life of steel bars is about 7200 days,2900 days,4500 days,and 2000 days,respectively,in A,B,C,and D solutions,while the life of concrete in the solutions is about 10000 days,6500 days,5500 days,and 5000 days,respectively.Moreover,the life of steel bars is more sensitive to chloride,while the life of concrete is more sensitive to sulfate.
作者
路承功
魏智强
乔宏霞
李刊
李琼
乔国斌
LU Chenggong;WEI Zhiqiang;QIAO Hongxia;LI Kan;LI Qiong;QIAO Guobin(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,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)
出处
《湖南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2021年第7期119-128,共10页
Journal of Hunan University:Natural Sciences
基金
国家自然科学基金资助项目(51168031,51868044)
中铁一勘院科研开发基金项目(13-24-01)
兰州理工大学红柳一流学科建设计划资助项目。
作者简介
路承功(1991—),男,甘肃平川人,兰州理工大学博士研究生;通信联系人:乔宏霞,E-mail:qiaohx7706@163.com。
