Assessment of the lead and zinc contaminations on the strength and physical properties of sand mixed with kaolinite, bentonite, and zeolite fines

Karimian, Akram

Abstract

The concentration of heavy metals in soil layers has increased due to the rapid development of the industry. Lead and zinc are two frequent heavy metal contaminants in soil. This paper aims to study the effect of these types of contaminants on different fines, including kaolinite, bentonite, and zeolite mixed with sand. First, mixtures of sand and kaolinite, bentonite, and zeolite were prepared, then they were contaminated by two contaminants of lead and zinc nitrates, separately. Consolidated undrained triaxial tests, Soil Conservation Service (SCS) double hydrometer tests, scanning electron microscope (SEM), Atterberg limits, and pH determination tests were conducted on the soil samples to investigate the changes in the strength and microstructure in the presence of heavy metals. In general, triaxial test results showed that various parameters influence the strength results of these heavy metal-contaminated sandy soil samples such as type, percentage, and structure of the fine portion, type, and concentration of contaminants, bonding mechanism of fine grains, and ion exchange capacity. For instance, in the presence of kaolinite (and kaolinite-zeolite mixtures), contamination with lead decreased the strength of soil samples, but in the soil mixtures containing bentonite (and bentonite-kaolinite mixtures), an opposite trend was seen. The plasticity index of mixtures containing kaolinite and zeolite increased in the presence of heavy metal contaminants, but it decreased when the fine portion of the soil was bentonite. Heavy metal contaminants decreased the pH of all soil mixtures and made them to be acidic. The results of the SCS double hydrometer test and SEM indicated that contaminated kaolinite and zeolite soil mixtures have a dispersed structure, while bentonite soil mixtures are not dispersive.

Citation

Karimian, A. (2024). Assessment of the lead and zinc contaminations on the strength and physical properties of sand mixed with kaolinite, bentonite, and zeolite fines. Bulletin of Engineering Geology and the Environment, 83, Article 250. https://doi.org/10.1007/s10064-024-03756-0

• Journal Article Type: Article
• Acceptance Date: May 21, 2024
• Online Publication Date: May 28, 2024
• Publication Date: 2024-06
• Deposit Date: Jun 19, 2024
• Journal: Bulletin of Engineering Geology and the Environment
• Print ISSN: 1435-9529
• Electronic ISSN: 1435-9537
• Publisher: Springer
• Peer Reviewed: Peer Reviewed
• Volume: 83
• Article Number: 250
• DOI: https://doi.org/10.1007/s10064-024-03756-0
• Public URL: https://durham-repository.worktribe.com/output/2486549