盐渍土环境下钢筋混凝土恒电流加速锈蚀试验及可靠性分析

Constant Current Accelerated Corrosion Test and Reliability Analysis of Reinforced Concrete in Saline Soil Environment

摘要:

采用恒电流加速锈蚀试验，结合石蜡层控制氯离子扩散路径的方法，将钢筋混凝土一维和二维试件作为研究对象，结合极化曲线（LPR）、氯离子含量分析、宏观形貌分析、扫描电子显微镜（SEM）和能谱分析（EDS）等手段，研究了盐渍土环境下钢筋混凝土的恒电流加速锈蚀规律.建立了基于可靠性的恒电流加速锈蚀与氯离子扩散腐蚀双因素作用下钢筋混凝土的劣化模型.结果表明：劣化模型推导的一维和二维试件平均寿命分别为927、618 h，石蜡层能有效隔离腐蚀性离子，实现单加速因素控制试件劣化的试验目的；钢筋混凝土的劣化主要受恒电流加速锈蚀与氯离子扩散腐蚀双因素耦合作用的影响；钢筋混凝土在恶劣环境下服役，建议以“前防锈，后防渗”的研究思路探索，即正常服役期间重点关注由钢筋锈蚀引起的腐蚀劣化，裂缝出现后重点关注由氯离子扩散引起的腐蚀劣化.

Abstract:

The one-dimensional and two-dimensional reinforced concrete specimens were used as research objects in a constant current accelerated corrosion test combined with the method of controlling chloride ion diffusion path with a paraffin layer. The galvanostatic accelerated corrosion law of reinforced concrete in a saline soil environment was studied using polarization curve（LPR）， chloride ion content analysis， macroscopic morphology analysis， scanning electron microscopy（SEM）， and energy dispersive analysis（EDS）. A reliability-based degradation model of reinforced concrete under the action of galvanostatic accelerated corrosion and chloride diffusion corrosion was established. The results show that the average life spans of the one-dimensional and two-dimensional specimens deduced by the deterioration model are 927 and 618 h， respectively. The paraffin layer can effectively isolate the corrosive ions and achieve the test purpose of controlling the deterioration of the specimens by a single acceleration factor. The deterioration of reinforced concrete is mainly affected by the coupling effect of constant current accelerated corrosion and chloride ion diffusion corrosion. When reinforced concrete is used in harsh environments， it is recommended to explore the research concept of “pre-rust prevention， afterwards anti-seepage”， which means that during normal service the focus should be on corrosion and deterioration caused by corrosion of steel bars， and after cracks appear the focus should be on the corrosion and deterioration caused by the diffusion of chloride ions.