Electrochemical behaviour of an austenitic stainless steel reinforced concrete in the presence of starch and cellulose admixtures

The electrochemical behaviour of an austenitic stainless steel embedded in concrete containing various proportions (5%, 10%, 15%, 20% and 25%) of starch and cellulose admixtures in contact with one molar solution of sodium chloride was studied. The electrode potential measurements were determined using a digital voltmeter with zinc rod reference electrode. Surface passivation was observed at 10–20% starch content, while 5–10% cellulose admixture was required to enhance surface passivation of the reinforced austenitic stainless steel. The synergetic effect of the two admixtures occurred at 5% starch and 15% cellulose, and produced good film stability. These deductions were attributed to the alteration in the composition of the concrete medium, which was brought about by the replacement of hydroxyl group in the structures of the admixtures by the aggressive chloride ions. There was an excess hydroxyl group released into the concrete medium, which created an excess alkaline and passivating environment for the reinforcing austenitic stainless steel (ASS) within the concrete.