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UBC Theses and Dissertations

A novel functionalized composite coating for controlling bio-corrosion in wastewater concrete pipes Roghanian, Negar


Bio-corrosion in sewage pipes is mainly caused by the diffusion of aggressive solutions and in-situ production of sulfuric acid by sulphur-oxidizing microorganisms which affect the physicochemical properties of concrete pipes. In this study an accelerated pilot-scale experimental setup is designed and built to replicate conditions in sewage transport systems as well as the bacterial induced corrosion processes in pipes. The reliability of the accelerated set-up is evaluated by conducting different tests on corroded samples over a 6 months period. In addition to the parameters such as weight loss and pH measurements that have been investigated by previous authors, variations in corrosion depth, flexural strength and absorption were also studied. Prevention of concrete bio-corrosion usually requires modification of concrete mix or application of antimicrobial coatings on the inner surface of the pipe. The composition of the coating is a key factor in controlling resistance to bio-corrosion which is dependent on the neutralization capacity of the material or its ability to prevent the growth of bacteria. The most common method for controlling the growth of bacteria is using bioactive chemicals (biocides) which are essentially toxic compounds. Undesired leaching of biocides to the surrounding environment as well as their short bio-resistance lifetime have increased the need for more efficient, environmental friendly and long-lasting alternatives. In this study, multiphase composite coatings are developed and tested. Controled-release mechanism was implemented inside the coating by mixing the binder matrix with functionalized sodium bentonite clay impregnated with zinc oxide and solidifying the antibacterial agent in 3D framework of coating material. Tensile strength, chemical resistance, leaching stability, microstructure and resistance to bio-corrosion in the accelerated chamber were investigated. Results show that the developed antibacterial coating can create a corrosion-resistant and effective physical/chemical barrier on concrete wastewater pipes and protects the concrete from bio-acid. Moreover, coatings successfully immobilized antibacterial agents inside the matrix and increased bio-resistant lifespan and durability of the repair material. This would likely lead to an increase in the service life of aged/corroded concrete pipelines.

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Attribution-NonCommercial-NoDerivatives 4.0 International