新老混凝土的钢筋加速锈蚀  

Accelerated Corrosion of Steel Bars in New and Old Concrete Structures

作　　者：张菊辉[1] 衣存浩 王诗昆 管仲国[2] ZHANG Juhui;YI Cunhao;WANG Shikun;GUAN Zhongguo(College of Environment and Architecture,University of Shanghai for Science and Technology,Shanghai 200093China;State Key Laboratory for Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092 China)

机构地区：[1]上海理工大学环境与建筑学院,上海200093 [2]同济大学土木工程防灾国家重点试验室,上海200092

出　　处：《硅酸盐学报》2022年第8期2096-2103,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金项目(51878491,51408359)。

摘　　要：目前,学者们围绕氯盐侵蚀引起的钢筋锈蚀及混凝土保护层开裂开展了大量研究,但主要针对整体浇筑钢筋混凝土结构,对新老混凝土结构的耐久性研究较少。通过设计制作8块水灰比分别为0.60与0.53的整体浇筑与二次浇筑混凝土试件,采用半浸泡通电加速锈蚀试验,研究二次浇筑试件在钢筋理论锈蚀率分别为4%、6%、8%时的混凝土表面锈胀裂缝发展规律以及锈后钢筋的力学性能变化,并与整体浇筑试件进行对比。结果表明:整体浇筑混凝土试件只产生纵向顺筋裂缝;二次浇筑混凝土试件先产生界面横向裂缝,后产生顺筋纵向裂缝。整体浇筑试件中钢筋为均匀锈蚀,二次浇筑试件钢筋为非均匀锈蚀,且界面处钢筋锈蚀最严重。由于新老混凝土结合面处钢筋截面损失严重,二次浇筑试件相比整体浇筑试件,钢筋力学性能明显下降。混凝土强度对整体浇筑试件内钢筋力学性能的影响可以忽略,但对二次浇筑试件的影响较大。Until now,many studies have been carried out to investigate the effect of reinforcement corrosion on concrete cracking due to chloride attack,but they mainly focus on monolithic reinforced concrete structures,and few studies on the durability of new and old concrete structures.Eight integral casting and secondary casting concrete specimens with different water-cement ratios(i.e.,0.60and 0.53)were fabricated,and the semi-immersion accelerated corrosion was examined.The development law of rust expansion cracks on the concrete surface and the changes in the mechanical properties of the rusted steel bars for the secondary-casting specimens were investigated and compared with the integral-casting specimens at different theoretical corrosion rates of steel bars of 4%,6%and 8%,respectively.The results show that the integrally poured concrete specimens only produce longitudinal cracks along the reinforcement,while the secondary-casting concrete specimens firstly produce interfacial transverse cracks and then produces longitudinal cracks.The steel bar in the integral-casting specimen is uniformly corroded,while the steel bars in the secondary pouring specimens are non-uniformly corroded,and the steel corrosion at the interface between unused and used concrete occurs most serious.The mechanical properties of the steel bars are reduced in the secondary-pouring specimens compared to the integral-pouring specimens due to the serious loss of the steel bar section at the interface between unused and used concrete.The influence of concrete strength on the mechanical properties of steel bars in the integral-casting specimens can be ignored,but it has an influence on the mechanical properties of steel bars in the secondary-casting specimens.

关 键 词：新老混凝土 锈蚀率 裂缝宽度 钢筋锈蚀 

分 类 号：TU528.1[建筑科学—建筑技术科学]