PSI - Issue 33

Francesco Freddi et al. / Procedia Structural Integrity 33 (2021) 371–384 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3.3. Double side diffusion: notched specimen The second test has been performed to evaluate the differences which arise in the crack pattern due to the presence of pre-existing cracks. The same parameters of the previous test have been used. A notch has been introduced on the bottom side to account for the presence of a pre-existing crack from which carbon dioxide can diffuse from a closer position to the steel rebar as shown in Fig. 7. The results reported in in Fig. 8 show the carbon dioxide concentration, the carbonation profile and the crack pattern. The first raw reports the results at the crack nucleation while the second raw reports the different profiles at the end of the simulation. It can be noted how the results change accordingly to the presence of a pre-existing crack as it affects the path from which the carbonation profile advances toward the reinforcement bar. Crack evolution is also affected as the corrosion process leads to earlier formation of rust deposits toward the notch.

Fig. 7 Double side diffusion: notched specimen domain

4. Conclusions The carbonation induced corrosion cracking phenomenon has been investigated and a numerical model which is capable to describe the complete process has been developed, catching important aspects of the physical problem:  the model accounts for changes in the external environmental condition reflecting them into the obtained crack pattern;  changes to the material mechanical parameters due to the concrete carbonation process are considered and actively affecting the cracks nucleation and evolution process;  formation of rust deposits, responsible of the swelling mechanism of the steel rebars, is modelled and used as a loading for the mechanical problem;  the phase-field approach provides crack patterns which reflect the environmental conditions as well as changes of the domain geometry.