Evaluation of Natural and Industrial Inhibitors on the Durability of Concrete and Steel in Saline Environments

In saline and marine environments, steel and the penetration of chlorides in concrete initiate and promote the rapid and progressive deterioration of structures, resulting in a loss of performance, increased maintenance needs, and a potential catastrophic failure. This has been the motivator of research in Peru to look for natural and sustainable inhibitors of a lesser ecological footprint, as the industrial inhibitors are far more detrimental, i.e., to the native plants. This research studied the relative performance of commercial vs. natural additives of steel and concrete in saline environments. In identifying optimal concentrations, plant extracts and microcapsules of avocado oil in varying concentrations were prepared. ASTM G31, G59, and C876 were the tests for corrosion measurement of the steel, and ASTM C1202 was for the chloride ion permeability. Seventeen variants were analysed with three replicates per material type. The results showed that the 75% avocado pulp coating achieved efficiencies of up to 85% on steel, similar to the industrial inhibitor. Likewise, apple and eucalyptus extracts achieved average efficiencies of over 69%, significantly reducing the likelihood of corrosion. Specifically, the 1% avocado oil microcapsule outperformed the commercial inhibitor with an efficiency of 78%, while apple and eucalyptus extracts achieved 74% and 73%, respectively, all classified as low permeability. In conclusion, natural additives, applied with appropriate formulations, can match or exceed the performance of industrial inhibitors, constituting a technical, economical, and ecological alternative for the protection of structures in marine and saline environments.