混凝土冻融循环退化过程中的孔隙发展与钢筋锈蚀试验研究  

Experimental Study on Pore Formation and Reinforcement Corrosion in Concrete During Freeze-Thaw Cycles

作　　者：张海龙[1] 王社良[1,2] 袁晓洒 ZHANG Hai-long;WANG She-liang;YUAN Xiao-sa(Key Laboratory of Concrete Structure Safety and Durability of Shanxi Province,Xijing University,Xi’an 710123,China;School of Civil Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China)

机构地区：[1]西京学院陕西省混凝土结构安全与耐久性重点实验室,陕西西安710123 [2]西安建筑科技大学土木工程学院,陕西西安710055

出　　处：《材料保护》2022年第7期102-109,共8页Materials Protection

基　　金：陕西省教育厅专项科学研究项目(19JK0911)资助。

摘　　要：针对混凝土在冻融循环过程中的退化问题,对退化过程中的孔隙发展以及孔隙发展引起的钢筋锈蚀进行研究。提出采用核磁共振技术对混凝土在冻融循环退化过程中的孔隙发展进行表征,采用电化学工作站对钢筋混凝土在冻融循环退化过程中的钢筋锈蚀发展进行研究。结果表明:混凝土在冻融循环退化过程中,T_(2)(驰豫值)谱中有3个波峰,其中表示试件内部的微细小裂缝的主峰面积占总面积的80%左右。随着冻融循环的进行,T_(2)谱中第一波峰(主峰)的面积呈指数形式增长。腐蚀电流密度和冻融循环次数之间服从指数关系,腐蚀电流密度和孔隙率之间服从线性关系。在175个循环后A-2组钢筋均已达到中等锈蚀状态,而B-2组试件则仍处于低锈蚀状态,表明添加粉煤灰可以提高混凝土的抗盐冻性能.Aiming at the problem of the degradation of concrete in freeze-thaw cycles,the pore formation and the consequent reinforcement cor-rosion in the degradation process were studied.The nuclear magnetic resonance(NMR)technology was proposed to characterize the pore for-mation of concrete during the freeze-thaw cycle degradation,and the electrochemical workstation was used to study the development of rein-forcement corrosion in the reinforced concrete in the process of above-mentioned degradation.Results showed that there were three peaks in T_(2)(relaxation value)spectrum of concrete during the freeze-thaw cycle degradation.The main peak area representing the micro cracks in the specimen accounted for about 80%of the total area.As the freeze-thaw cycle progressed,the area of the first peak(main peak)in T_(2) spectrum increased exponentially.Meanwhile,the relation between the corrosion current density and the number of freeze-thaw cycles was exponential,and the relation between corrosion current density and porosity was linear.After 175 cycles,the reinforcements of group A-2 reached a medium corrosion state,while the specimens of group B-2 were still in a low corrosion state,indicating that adding fly ash could improve the salt-freez-ing resistance of the concrete.

关 键 词：混凝土 冻融循环 核磁共振 T2谱 极化曲线 

分 类 号：TU525[建筑科学—建筑技术科学]