A study on the Durability Enhancement of Reinforcement Concrete structures employing Hybrid corrosion inhibitor Duc Thanh TRAN

Abstract

The marine environment in South Korea presents significant challenges to the durability of reinforced concrete structures against corrosion. With coastal regions exposed to high humidity, saltwater, and corrosive agents such as chlorides and sulfates, the deterioration of these structures is accelerated. The proximity to saltwater bodies and industrial activities intensifies the risk of chloride ingress and chemical exposure, further compromising the integrity and service life of marine infrastructure. Ensuring the long-term sustainability and safety of critical structures such as ports, harbors, and offshore platforms requires advanced corrosion resistant technologies, innovative materials, and efficient maintenance strategies. Addressing the durability concerns of reinforced concrete in the South Koreamarine environment requires a multidisciplinary approach. Collaborative efforts among researchers, engineers, policymakers, and industry stakeholders are crucial to investigating corrosion mechanisms, developing effective preventive strategies, and implementing rigorous maintenance protocols. By advancing corrosion-resistant technologies and materials, South Korea can extend the service life of its marine infrastructure, supporting economic growth and protecting coastal regions from the detrimental effects of corrosion. Therefore, the use of corrosion inhibitors for steel bars against active corrosion in RC structures is a wise choice due to its easy approach, low prices, and ecofriendliness. L-arginine (LA), an amino acid, and sodium phosphate tribasic (TSP), a phosphorous compound, have individually demonstrated corrosion inhibition properties in previous studies. Protection of steel reinforcement in reinforced concrete (RC) structures against corrosion is a critical concern for ensuring their durability and service life. One promising approach is the use of a hybrid corrosion inhibitor comprising LA and TSP. This study aims to investigate the effectiveness of this hybrid inhibitor by evaluating its optimal composition, corrosion inhibition mechanisms, and its impact on the mechanical and electrochemical properties of concrete. The findings of this research can contribute to the development of innovative strategies for corrosion protection in RC structures, leading to extended service life and improved sustainability in the construction industry. This research study aims to evaluate the effectiveness of a hybrid corrosion inhibitor, consisting of LA and TSP, in protecting steel rebar in reinforced concrete (RC) structures, with the objective of finding a noble hybrid corrosion inhibitor for corrosion prevention and prolonging service lives of RC structures. The investigation encompasses a comprehensive analysis of the hybrid inhibitor of performance and its impact on various corrosion-related factors. Through meticulous experimentation, it was determined that an optimal mixture, labeled L2P2, comprised 2 wt. % LA and 0.25 wt. % TSP, exhibited the highest corrosion inhibition efficiency of 95 %. This exceptional performance can be attributed to the formation of stable and homogeneous P-zwitterions-(Cl)- Fe complexes, which effectively permeate the concrete matrix, providing a robust protective barrier against corrosion. Furthermore, the incorporation of the hybrid corrosion inhibitor demonstrated significant improvements in workability without causing substantial alterations in the air content, porosity, and chloride diffusion coefficient of the concrete mixture. The increase in hybrid inhibitor content was found to have an acceptable impact on compressive strength, with the HI-3 sample meeting the required industry standards. The collaboration between the hybrid corrosion inhibitor and RC samples resulted in enhanced corrosion resistance properties, including an elevated critical chloride concentration and an extended corrosion initiation time. Notably, the HI-3 sample exhibited superior complex-plane impedance and phase angle values compared to other samples, indicating the presence of a highly protective and stable passive film. To further validate the efficacy of the hybrid corrosion inhibitor, deterministic and probabilistic service life models in Life 365 were employed. These models consistently predicted an increase in service life as the inhibitor content in the concrete mix increased. This reinforces the practical applicability of the hybrid corrosion inhibitor in engineering industries, indicating its potential to mitigate corrosion-related deterioration and promote the longevity of RC structures. In summary, the collaboration between the hybrid corrosion inhibitor and the RC samples exhibited improved corrosion resistance properties and a great guarantee of mechanical properties, leading to an extended service life, as corroborated by deterministic and probabilistic models. These findings underscore the scientific viability and practical potential of the hybrid corrosion inhibitor to enhance the durability and sustainability of RC infrastructures. This research study comprises a total of seven chapters, each of which contains the following content: Chapter 1, Introduction covers the background, motivation, purpose, methodology, scope, and overall structure of this research. Chapter 2, Comprehensive review of relevant literature, including corrosion types, corrosion mechanisms, factors influencing corrosion, anti-corrosion methods, comparison of commercial corrosion inhibitors, determination methods for chloride threshold, models for chloride penetration, and durability design methods. Chapter 3, Assessment of the hybrid inhibitor focuses on determining the optimal quantity and elucidates its corrosion inhibition mechanism. Chapter 4, Investigation of the impact of the hybrid corrosion inhibitor on various mechanical properties of concrete, such as setting time, air content, slump, compressive strength, porosity, and chloride diffusion coefficient. Chapter 5, Examination of the effects of the hybrid inhibitor on the electrochemical properties of reinforced concrete, including the corrosion resistance mechanism, corrosion rate, passive film kinetics, and critical chloride concentration. Chapter 6, Utilization of deterministic and probabilistic approaches, employing gathered experimental data and support from Life 365 software, to predict the results of the study. Chapter 7, Summary and conclusions derived from each respective chapter, consolidating the key findings and implications of this research.