Corrosion of Steel Bars in Concrete with the Variation of Microstructure of Steel-Concrete Interface

Abstract

An experimental investigation was carried out on chloride induced corrosion of steel bars in concrete under marine environment with the variation of micro-structure of steel-concrete interface. To create the variation of micro-structure of steel-concrete interface, steel bars coated with cement paste of different W/Cs and cement types were used. For investigation, cylindrical concrete specimens were made with steel bars (with and without cement paste coating). W/C ratios of cement paste coat were 0.3, 0.5, 0.7 and 1.0. The specimens were exposed to an accelerated seawater exposure controlled with automatic wetting and drying. The specimens were tested till 45 cycles in the exposure. Test items include compressive strength of concrete, chloride ingress into concrete, electrochemical evaluation of corrosion, microscopic investigations of steel-concrete interface by optical microscope, scanning electron microscope (SEM), and linear traverse. It is revealed that the initiation of corrosion is significantly influenced by the nature of micro-structure of the steelconcrete interface, such as size of voids at the steel-concrete interface.

Applicability of Electrochemical Chloride Extraction to Concrete Made With Different Binders

“…The results found imply as well that the driving force has predominant influence on the chloride transport on this case. Generally, the steel-concrete interface (SCI) has relevant influence on the structural durability and performance of concrete, being even more crucial when it comes to chloride induced corrosion behavior (Mohammed et al, 2015). Usually chlorides can penetrate the concrete through capillary pores, since they make a network that enables ionic transport (Mehta and Monteiro, 2014).…”

Service life optimization and life cycle assessment of concrete using SCMs as partial replacement of cement

“…One of the numerous critical parameters for regulating the service life of the infrastructure is the way of chloride penetration inside the concrete. That may theoretically be established by mathematical modelling of a chloride transportation mechanism [9]. A typical acceptable mathematical model to describe the fluctuating diffusion ways of chloride infiltration in a concrete infrastructure is diffusion equating based on Fick's second law of diffusion [10].…”

Investigation of passive layer formation on steel rebars in foamed concrete

“…Voids formed due to bleed water accumulating under reinforcement have been shown to promote corrosion and it has been suggested that lower alkalinity of bleed water has resulted in reduced passive layer protection . The entrapped air voids in contact with reinforcement has been suggested as a source of corrosion and it has been proposed that if proper and tight adhesion of reinforcement with paste is obtained and voids are prevented, a much improved performance against corrosion can be achieved …”