Theoretical-Experimental Analysis of Corrosion-Cracking Coupling in Reinforced Concrete Structures

Resumo

The corrosive process is not a recent problem, however, even nowadays it is one of the most common
problems on reinforced concrete structures, whether by execution inconveniences, by the high relation
water/cement of concrete or even by the negligence in the project stage of consideration of an adequate covering
which attends the corresponding aggressiveness of the class. Therefore, the previous determination of the evolution
of the corrosion along time shows itself as an allied tool in the reduction of costs with maintenance and/or repairs.
In this context, the following paper aimed to identify experimentally, in beams, the influence of the corrosion
evolution by chloride ions in the advance of degradation from the elements of reinforced concrete. A process of
acceleration of the corrosion was used through the sprinkling of a sodium chloride solution (NaCl) via a sprayer,
simulating the effect of wetting/drying in the breams. Simultaneously, the beams were under mechanic
solicitations, so as the experiment advanced the deflections, cracking and especially the corrosion potential in the
rebars were evaluated. Later, after this identification, the experimental analysis was combined with thermodynamic
models based on the Lumped Damage Mechanics to analyze reinforced concrete structures that are subject to
chemical action in addition to mechanical stresses. It was found that all beams subjected to the spraying of
chlorides showed a greater than 90% probability of being under corrosion and the highest values of corrosion
potential were concentrated in the central region of the beam, where the damage was also higher. Furthermore, the
presence of corrosion increased the values of damage and plastic rotations in the beams, and this increase, in turn,
contributed to the increase in corrosion rates. However, the presence of moisture due to the NaCl solution affected
the creep and consequently, the displacements suffered over time.