Influence of organic corrosion inhibitors on steel corrosion in concrete under the coupled action of freeze–thaw cycles and chloride attack

Abstract

Organic corrosion inhibitors (OCIs) are commonly used to enhance reinforced concrete durability in the marine environment. In this contribution, the effects of OCIs on steel corrosion in concrete exposed to coupled deterioration of freeze–thaw cycles and chloride attack have been evaluated. Concrete samples with mild steels were mixed with three commonly used OCIs (alcoholamines-, carboxylic acids-, and esters-based), and exposed to freeze–thaw cyclic test in a 3% NaCl solution. The corrosion-resistance mechanisms of OCIs on steel corrosion were revealed using the open circuit potential test (OPC) and electrochemical impedance spectroscopy measurement (EIS). The steel–concrete interface micromorphology was observed by the optical microscope and the scanning electron microscope (SEM). The results showed that salt-frost resistance of concrete incorporated with alcoholamines-, carboxylic acids-, and esters-based OCIs was improved by about 50%, 350% and 200%, respectively. However, internal damage caused by freeze–thaw cycles was aggravated after adding easter-based OCIs due to the reduction in pore diameter caused by hydrophobic calcium salt lining. Alcoholamines- and carboxylic acids-based OCIs could significantly delay the steel de-passivation. Alcoholamines could increase the passive film resistance and carboxylic acids could replace the chloride attached to the steel surface.