Author(s): Nurzhan Kairatuly and Zhanna Moldabekova

Abstract: Chloride ingress is a significant cause of steel reinforcement corrosion in cementitious materials. This study investigates the adsorption behavior of clinoptilolite, a natural zeolite, as a supplementary cementitious material (SCM) to mitigate chloride penetration. The study found that 15% clinoptilolite replacement achieved up to 80% chloride reduction at a depth of 20130 mm, validated by Langmuir adsorption modeling (R² = 0.96). Compressive strength showed minor reductions (7110%) but was considered acceptable. The findings suggest clinoptilolite as a sustainable solution for improving durability in chloride-prone environments.Chloride ingress is a significant cause of steel reinforcement corrosion in cementitious materials, leading to structural deterioration and reduced service life. This study investigates the adsorption behavior of clinoptilolite, a natural zeolite, as a supplementary cementitious material (SCM) to mitigate chloride penetration and enhance the durability of reinforced concrete. The objectives of this study were to (i) evaluate the chloride adsorption capacity of clinoptilolite-modified cementitious composites, (ii) determine its effect on compressive strength, and (iii) elucidate the mechanisms of chloride containment.Materials used included natural clinoptilolite with confirmed crystalline structure and specific surface properties, Type I Portland cement, and NaCl solutions for chloride exposure. Cementitious samples were prepared by partially replacing cement with 5%, 10%, and 15% clinoptilolite. Accelerated chloride penetration tests were performed following ASTM C1202 standards, and chloride content at different depths was determined using potentiometric titration. Adsorption mechanisms were analyzed using Langmuir and Freundlich isotherm models, while microstructural properties were evaluated using SEM and EDS techniques. Details on the source of clinoptilolite and its particle size distribution were added for clarity and reproducibility.The results revealed a dose-dependent reduction in chloride content, with 15% clinoptilolite replacement achieving up to 80% chloride reduction at a depth of 20130 mm compared to the control mix. The Langmuir adsorption isotherm model provided the best fit (R² = 0.96), indicating a monolayer adsorption process. Compressive strength tests showed minor reductions (7110%) with increased clinoptilolite content, attributed to its lower pozzolanic activity. Microstructural analysis confirmed the adsorption of chloride ions onto clinoptilolite surfaces.In conclusion, clinoptilolite significantly improves chloride resistance in cementitious materials, making it a viable and sustainable solution for enhancing the durability of reinforced concrete structures in chloride-prone environments.

DOI: 10.22271/27078361.2024.v5.i2a.58

Pages: 49-54 | Views: 72 | Downloads: 25

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