چكيده به لاتين
Concrete structures in marine environments are affected by various destructive factors and elements that cause damages to exacerbate over time and eventually lead to deterioration of the concrete structures. According to the evidences and reports of various failures, especially in tidal and splash zones of marine concrete structures with severe corrosion of steel bars due to the penetration of chloride ion of seawater, it can be seen that repairs and maintenance are inseparable parts of reinforced concrete structures in marine environments. Considering to the above, this research has tried to investigate the influence of patch repairs and applying overlays for more adaptation and protection on the performance and durability of reinforced concrete structures in corrosive marine environments.
In this research, by changing the physical and electrochemical properties of repair’s materials and overlays, the performance of the repairing system has been investigated. The various characteristics of repairing concretes and base concretes have been evaluated by using different tests such as compressive strength test, electrical resistance test, permeability test, water absorption test, rapid chloride penetration test (RCPT), rapid chloride migration test (RCMT) and etc.. Also by conducting experiments such as potential of the corrosion and the intensity of the corrosion current in modes of microcell and macrocell and etc. on the repairing system, the effects of repair’s materials and overlays on corrosion processes in reinforced concrete structures have been evaluated. For further achieve research purpose, seven slabs with different parts of the repairing system and the same base concrete have been constructed. Three slabs have only been repaired locally and three other slabs are also covered with various overlays in addition to the patch repairs. The results show that the electrical resistance of repairing concrete is a controlling parameter in the macrocell corrosion rate, however, this effect is not significant. If applying of overlay on the repairing system be able to limit the diffusion of oxygen and moisture greatly, it can have a significant effect on the macrocell corrosion rate, while most overlays even increase the macrocell corrosion rate by increasing the electrolyte environment.
Keywords: concrete durability, repairs, overlay, corrosion, marine structures.
