混凝土构件中钢筋锈蚀的中子断层扫描成像

Neutron Tomography of Steel Corrosion in Steel Reinforced Concrete

制备了小型混凝土构件,通过三点弯曲诱导裂缝和氯盐溶液干湿循环加速其中钢筋锈蚀,采用自然电位法监测钢筋的腐蚀电位,并采用中子断层扫描成像技术对钢筋锈蚀产物分布进行了分析.结果表明:钢筋混凝土构件经过85次氯盐溶液干湿循环后,采用中子断层扫描成像技术对其进行三维扫描成像,可直观呈现钢筋锈蚀产物分布状况;钢筋锈蚀产物集中分布于裂缝断面钢筋与基体界面的底部区域,并沿界面逐渐向外扩展,符合氯盐诱导钢筋锈蚀的坑蚀规律.这为研究混凝土结构中钢筋的锈蚀机理提供了一种新的试验方法.

Small size of steel reinforced concrete beam was prepared. Cracks have been induced by threepoint bending test. Through wetting-drying cycles with NaC1 solution, the corrosion of reinforcing steel in the RC beam has been accelerated. The corrosion potential of the carbon steel reinforcement has been measured by using the natural potential method. The corrosion product distributions on the steel surface have been analyzed by means of neutron tomography. Results obtained indicate that after 85 wetting-drying cycles, the reinforced concrete beam can be scanned in three dimensions by the technique of neutron tomography. The spatial distributions of corrosion products around the steel reinforcement in the RC specimen can be visualized directly. The corrosion products are mainly concentrated at the interfaces between steel reinforcement and mortar matrix along the crack section. The corrosion products may gradually develop outwards along the steel at the interfaces. This phenomenon is in accord with the mechanism of pitting corrosion induced by chloride ions. A new experimental approach to study the corrosion mechanism of steel in reinforced concrete structures is provided.