PSI - Issue 17

S. Tsouli et al. / Procedia Structural Integrity 17 (2019) 268–275 S. Tsouli, A.G. Lekatou, C. Nikolaidis, S. Kleftakis/ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. Stress-strain curves of 316L and 304L rebars embedded in concrete with different FA contents after (a) 0 m and (b) 2 m of salt spraying.

3.2 Microstructure of corroded specimens Figure 5a-c reveals a fine surface state of 316L rebars after cyclic polarization in the slightly alkaline electrolyte (0, 20, 25 wt.% FA, respectively). Figure 6a shows a non-uniform, non-compact Ca-based oxide film on the steel surface (0% FA). Conversely, Figure 6b shows a compact film uniformly deposited on the 316L surface (20 wt.% FA); the increased Si on the steel surface manifests the positive role of the FA on the formation of a uniform protective film. Figure 7 shows that the 316L embedded rebars have retained a good surface state after 4 m of salt spraying.

Fig. 5. SEM cross-sectional micrographs of 316L rebars after cyclic polarization in a slightly alkaline electrolyte containing Ca(OH) 2 , acid rain simulating solution and (a) 0 wt.% fly ash, (b) 20 wt.% fly ash, (c) 25 wt% fly ash; ( wt.%: with respect to the dry mixture of Ca(OH) 2 ).