Evaluation of Chloride Diffusion and Corrosion Resistance in Reinforced Concrete Using Internal Curing and Shrinkage Reducing Admixtures

摘要

The properties of high-performance concretes obtained by the internal curing technique were studied inthe fresh and hardened states. In some of the concrete mixtures, fine normal weight aggregates werereplaced with lightweight aggregates (LWA) at 20?% vol. and ordinary portland cement was replacedby pulverized class F fly ash at 20?% by mass. Additionally, some mixtures were prepared including ashrinkage-reducing admixture, either as part of the mixing water or pre-soaked into the lightweightfine aggregates. The prepared concretes were subjected to degradation tests, such as acceleratedcarbonation and chloride ion deterioration. In addition, the reinforced concretes were analyzed throughelectrochemical corrosion tests with the linear polarization resistance technique. It was found that theinternally cured concretes presented a mechanical resistance similar to those reported for the referenceconcretes (conventional concretes), but provided a higher resistance to carbonation, rapid penetrationof chloride ions, and a lower chloride ion diffusion coefficient. The reinforcing steel structure in theinternally cured concretes showed lower corrosion currents (Icorr) and corrosion potentials (Ecorr) incomparison to the reference concretes. Therefore, the use of the internal curing technique in concreteswith pre-soaking in either water or a solution of shrinkage-reducing admixture can be considered as aviable alternative to extend the service life of concrete structures in contact with harmfulenvironments.