Enhancing the corrosion resistance of reinforcing steel under aggressive operational conditions using behentrimonium chloride

Aggressive operational conditions e.g. saline media and acidic gases, e.g., CO2 can increase the corrosion rate of reinforcing steel. Accordingly, the necessity to protect the steel under the above conditions without affecting the mechanical properties of the concrete is growing. Herein, the inhibition efficiency of a new corrosion inhibitor, behentrimonium chloride (BTC, C25H54ClN), is explored in a simulated-concrete pore solution (SCP) with 3.5 wt.% NaCl at different pH using electrochemical impedance spectroscopy (EIS) and polarization methods. Using only a 50 ?mol L?1 of BTC, we are able to measure an inhibition efficiency of 91, 79, and 71% in SCP solution with 3.5% NaCl at pH of 12.5, 10 and 7, respectively without showing any effect on the mechanical properties on the cured mortars. Temkin isotherm is used to describe the physisorption of BTC inhibitor on the steel surface. Also, the adsorption and influence of the inhibitor on the metal surface are characterized using the scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. In conclusion, this new inhibitor shows high corrosion inhibition efficiencies under different aggressive conditions and can be used in concrete to reduce the corrosion rate of reinforcing steel without decreasing the mechanical properties of the concrete. - 2019, The Author(s).The publication of this article was funded by the Qatar National Library.Scopu

Recent advances in corrosion resistant superhydrophobic coatings

Extreme water-repellent (superhydrophobic) coatings with water contact angle higher than 150° have caught the attention of corrosion researchers in the last decade as they can be used to protect metals and alloys against corrosion. The latter is a serious problem, as it can threaten human lives in addition to its deleterious effects on the economy and environment. Superhydrophobic coatings (SHCs) can be achieved by lowering the surface energy of a certain coating through combining some of its surface features at the microscale and nanoscales. Although SHCs can be prepared using many different easy techniques, none, to the best of our knowledge, has been applied, so far, on an industrial scale for protection against corrosion of metals and alloys. The present work explains the different models of superhydrophobic surfaces (SHSs) and reviews their fabrication and processing methods with a focus on the recent advances in the corrosion protection of the SHC. © 2018 Walter de Gruyter GmbH, Berlin/Boston.Acknowledgments: The authors gratefully thank the Center for Advanced Materials at Qatar University for the financial support

Reinforced Concrete Degradation in the Harsh Climates of the Arabian Gulf: Field Study on 30-to-50-Year-Old Structures

This paper presents the results of a field study carried out on three reinforced concrete (RC) structures built in the 1960s, 1970s, and 1980s to determine the main load (environmental) and the resistance (for example, the concrete quality and clear cover) factors affecting the durability of the infrastructure in the harsh environmental conditions of the Arabian Gulf region. The effects of degradation, such as the carbonation depths and chloride concentration profiles, in the columns, beams and slabs were determined from concrete core samples. To determine the durability factors, the concrete resistivity to electrical charge, the rapid chloride permeability, and the sorpitivity were measured. Digital image processing was performed to estimate the cement contents and the proportions of other ingredients used in the concrete samples. In most of the structural members, the chloride threshold for steel depassivation had been surpassed and the carbonation had reached the steel surface. The spalling of the concrete cover was observed with severe corrosion damage to the reinforcing bars. It is expected that this study will help understand the degradation phenomena in RC structures in the Gulf region and similar hot, humid, and saline environments. The results will help to establish the input parameters for the chloride diffusion and carbonation models in aggressive environmental conditions. Because the concrete quality directly impacts the initiation of many deterioration processes such as corrosion of the steel reinforcement and carbonation, the results could be used to predict the remaining service life of existing RC structures with similar concrete properties.The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of the Qatar Foundation) under the award NPRP 7-410-2-169