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Corrosion rate and corrosion product characterisation using Raman spectroscopy for steel embedded in chloride polluted fly ash mortar



Electrochemical impedance spectroscopy (EIS) and polarisation curves assisted by Raman spectroscopy were used to study the corrosion behaviour and to characterise the corrosion products of reinforcing steel embedded in fly ash mortars with and without chloride pollution. Two alkaline solutions with different soluble silica contents were utilised to activate the fly ash. After 720 days of experimentation the reinforcing steel embedded in fly ash mortar without chlorides remained passive, while the specimens in fly ash polluted with chloride ions (0.4 and 2%) yielded current density values of the order of 2 × 10−5 A/cm2, typical of an active state. The main corrosion products identified on the steel surface were less crystallised phases of iron oxyhydroxide hydrates and goethite (α-FeOOH) or lepidocrocite (γ-FeOOH).