Corrosion induced by industrial coal-fired flue gas: deterioration mechanism of an existing concrete structure

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This article investigated the corrosion deterioration behavior of concrete structures exposed to industrial coal-fired flue gas for 12 years. The concrete’s macro-mechanical properties, pore structure characteristics, and micro-properties were tested by in-situ and laboratory tests along the height and depth. The test results indicated that different corrosion mechanisms were occurred inside the concrete along the corrosion depth direction. In the shallow concrete zone (0–8 mm), sulfation is predominant, with gypsum (Gyp) as the primary product. O 4 2 − In the coexistence concrete zone (8 ∼ 14 mm), both sulfation and carbonation are present, with the pH increasing from 8.0 to 11.0. Beyond 14 mm, S O 4 2 − and Gyp are no longer detected. In the deep concrete zone (14–18 mm), carbonation is the dominant process, with CaCO3 as the main product. Considering the impact of the effective diffusion coefficient and SO2 concentration gradient distribution, a prediction model for the neutralization depth of concrete in industrial coal-fired flue gas has been proposed.