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Mössbauer and xrd analysis of corrosion products of carbonated alkali-activated slag reinforced concretes

Abstract:

Steel bars embedded in an alkali-activated slag (AAS) concrete have been exposed (after curing for 28 days) to an accelerated carbonation chamber (3 % CO2, 65 % relative humidity (RH), and 25°C temperature) and to a laboratory environment (0.03 % CO2, 65 % RH, and 25°C). Ordinary Portland cement (OPC) was also tested for comparative purposes and exposed to identical experimental conditions. Corrosion products generated at the steel/concrete interface were characterized using Mössbauer spectrometry and the X-ray diffraction (XRD) technique. The main compounds were magnetite (Fe3O4), wuestite (FeO), and goethite (a-FeOOH). The morphology of corrosion products was analyzed using the scanning electron microscopy technique (SEM).