Open Collections

Kandra, Darshan Chowdary

University of British Columbia

Corrosion in concrete sewers results from both biotic and abiotic processes. Microbially induced concrete corrosion (MICC) is a multifaceted phenomenon driven by the metabolization of sulfate-rich wastewater by sulfate-reducing bacteria in anaerobic conditions, producing hydrogen sulfide as a byproduct. This hydrogen sulfide undergoes chemical or biological oxidation and reacts with the alkaline and porous concrete surfaces of the sewer. Consequently, the reaction-transport mechanisms between the hydrogen sulfide and substrate causes the pH of the concrete surface to decrease, creating an environment conducive to the growth of sulfur-oxidizing bacteria. These bacteria further metabolize hydrogen sulfide, converting it into sulfuric acid, thus perpetuating the cycle of Microbially Induced Corrosion (MIC). Approximately 6% of the global GDP is utilized in repairing and maintaining pipes damaged by biocorrosion, highlighting its significant economic impact. However, current mitigation strategies have demonstrated inherent limitations. To combat MIC, cement-based/polymer coating methods have emerged as popular solutions due to their effectiveness, easy application, and cost-efficiency. However, effective coatings for MIC prevention require both antibacterial and anticorrosive properties. Unfortunately, traditional coatings which utilize heavy metals like tin, copper, and zinc as anti-microbial agents pose environmental hazards, thereby limiting their widespread use. Consequently, there is an increasing focus on the development of coatings that not only provide low cytotoxicity and genotoxicity but also possess antibacterial and anticorrosive properties, while maintaining compatibility with deteriorated substrate. In this study, the focus lies on exploring the potential of graphite, known for its reduced toxicity, corrosion resistant, and cost-effectiveness, as a biocide when encapsulated within calcium aluminate and geopolymer coating matrices. This research evaluates the mechanical properties and chemical stability of these newly developed coating materials. Additionally, the performance of these coating materials is tested under accelerated MIC conditions, and the antibacterial effectiveness is also assessed. Research findings from this study indicate promising results: graphite-doped composites demonstrate superior strength, durability, and bonding performance. Moreover, the graphite-incorporated coatings exhibit excellent resistance against biogenic acid attack, while both graphite and calcium aluminate-based coatings display antibacterial properties. Consequently, the developed coatings demonstrate potential in mitigating MICC.

Text

2024-04-19

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87900

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/