Title : EFFECT OF IMPRESSED CURRENT ON THE MICROSTRUCTURE OF CORRODED STEEL-CONCRETE INTERFACE
Authors : Rudrabir Ghanti and Hong Wong
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Price : 250
Abstract : The alkaline nature of concrete ensures that the corrosion initiation of reinforcing steel embedded in concrete takes a long time. Concomitantly, accelerated corrosion tests were carried out using impressed current till the crack initiation phase occurred as a result of which the testing period was reduced from years to a few weeks. An electrochemical cell was set up and direct current was impressed from the titanium mesh (acting as cathode) to the rebar (anode) through the concrete with the help of sodium chloride solution (electrolyte). Back-scattered electron images were obtained on flat, polished samples followed by image analysis to study the amount and distribution of corrosion products around the steel-concrete interface. It was found that impressed current technique was successful in simulating the natural corrosion process in terms of corrosion pattern, distribution and method of attack. The amount of steel loss did not increase in proportion to corrosion current as suggested by Faraday’s law. Other micro-structural factors like extent of micro-cracking, dense accumulation of corrosion product at the steel-concrete interface may play a significant role in steel section loss especially at higher corrosion rates. The degree of corrosion of ribbed bars was found to be more as compared to plain bars. Moreover, ribbed bar samples had a greater uneven and heterogeneous corrosion product distribution than plain bars. A detailed characterization of the effect of accelerated corrosion on the microstructure of the corroded steel-concrete interface is discussed.