Steel corrosion is major reason of the deterioration of reinforced concrete structures. Decreasing the transportation of erosion ions in concrete is one of effective methods to protect the steel from corrosion. In the present work, a novel nano-hydrophobic admixture is introduced to improve the ion-diffusion properties and the corrosion resistance of reinforced steel. Compared with unmodified concrete, the nano-hydrophobic admixture effectively decreases the water adsorption, water evaporation, and chloride ions transport in a concrete structure, and then improved the concrete’s durability. The concrete’s water adsorption decreased more than 78%, and the initial corrosion time of reinforced steel is prolonged more than one time by treatment with the nano-hydrophobic admixture. The inhibition penetration of the medium in concrete modified by hydrophobic nanoparticles is the key to provide the protective properties of steel reinforcement from chloride erosion.

1H-Perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) were developed as inhibitors for reinforcing steel in a simulated concrete pore (SCP) solution. Electrochemical measurements, contact angle experiments, scanning electron microscopy (SEM) and quantum chemical calculations were used to investigate the corrosion performance and adsorption mechanisms. The experimental results showed that owing to the structure of SPMD containing a 2-position sulfhydryl group, SPMD is superior to PMD as a corrosion inhibitor for HRB400 reinforced steel in the SCP solution, and its corrosion efficiency can reach more than 80%. Moreover, the introduction of nitrogen and sulfur atoms into the inhibitor not only can coordinate with Fe atoms to form strong bonds but also is useful for preventing charge transfer in the metal corrosion process. More importantly, the perimidine derivatives can spontaneously adsorb on iron, and the adsorption process obeys the Langmuir isotherm. The research results show that the perimidine derivatives can improve the durability of concrete structures.