海洋浪溅环境下功能梯度混凝土的防护性能分析

Analysis of protective performance of gradient structure concrete in marine splash zone

为了研究功能梯度混凝土(FGC)的耐久性防护效能,成型3种不同面层厚度的FGC复合体系和2种单层体系试件,并采用加速试验进行抗氯离子侵蚀性及抗钢筋锈蚀的对比分析。研究结果表明:FGC复合体系表层处的Cl含量明显低于OPC单层体系,并与MIF单层体系的相差不大。FGC复合体系可降低Cl侵入深度及侵入量,且其抗氯离子侵蚀性能力随面层厚度增大而增大,当面层厚度大于10 mm时,其抗侵蚀性与MIF单层体系相差不大。FGC复合体系抗钢筋锈蚀性好于OPC体系;研究还发现除FGC-20外,FGC复合体系的抗钢筋锈蚀性随面层厚度增大而增大。其原因是FGC-20中钢筋正好布置于两层结合处,两层材料的电化学\渗透性存在差异,导致内部钢筋锈蚀程度严重于其他厚度的FGC复合体系。可见合适的FGC复合体系可以经济而有效的提高混凝土结构的耐久性。

Two kinds of single-layer concrete specimens and gradient structure concrete with three different surface-layer thicknesses were prepared, and their protective performance were researched by conducting the rapid chloride ion penetration test and electrochemical corrosion test. The results show that the surface chloride ions content in OPC single-layer specimen is higher than in FGC bi-layer concrete and MIF single-layer concrete, but there is little difference between the last two; secondly, FGC bi-layer concrete and MIF single-layer concrete can significantly reduce chloride ion intrusion and depth; moreover, increased surface-layer thicknesses will increase the ability to resist chloride ion erosion in FGC bi-layer concrete. It is shown that there is little difference between FGC bi-layer concrete and MIF single-layer concrete when the surface-layer thickness is more than 10 mm in FGC bi-layer concrete. Thirdly, the corrosion of steel bar is increasing in the following order： OPC single-layer system, FGC-20 bi-layer system, FGC-10 bi-layer system, FGC-15 bi-layer system, and MIF single-layer system. The study also shows that the corrosion of steel bar in FGC-20 specimen is more serious than FGC-10 and FGC-15 specimens due of its steel bar arrangement in the two layer bonded joint, and the differences of electrochemical property and permeability between two materials. Therefore the appropriate FGC composite system can economically and effectively improve the durability of concrete structure.