Work

Effects of used motor oil and leachate on the geotechnical and microstructural properties of clays with different mineralogy

Year: 2025

Type: article

Abstract: • Effect of adding water, leachate and UMO on the geotechnical characteristics of CL, CB and SB is evaluated. • Adding leachate to the clays has a more PL, LL, PI, free swelling, MDD and OMC than the UMO. • Adding UMO to clay reduces optimum moisture. • Adding leachate to clay compared to water decreases the free swelling of CL, but the free swelling of SB is higher than CB and CL. In this study, the effect of adding water, leachate, and used motor oil (U.M.O) on the geotechnical and microstructural characteristics of three fine-grained soils with different mineralogy (clay in situ (CL), calcium bentonite and sodium bentonite) is evaluated. Atterberg limits, standard compaction, pH, atomic force microscopy (AFM), Scanning electron microscopy (SEM) and swelling index tests are performed. The results of this study demonstrated that the interaction between pollutant type and soil mineralogy significantly affects soils' geotechnical behavior. The plasticity index (PI) of sodium bentonite, calcium bentonite, and CL soil mixed with leachate increased by 43%, 25%, and 10%, respectively. In contrast, the addition of U.M.O reduced the PI of sodium bentonite, calcium bentonite, and CL soil by 72%, 66%, and 12%, respectively. The addition of leachate, compared to water, decreased the swelling of sodium bentonite, calcium bentonite, and CL soil by 25%, 21%, and 18%, respectively, due to the reduction in the diffuse double layer (DDL) thickness. The U.M.O., compared to water and leachate, caused the least swelling in all soil types due to its non-polar nature and low dielectric constant. The addition of leachate to sodium bentonite, calcium bentonite, and CL soils increased the optimum moisture content (OMC) by approximately 7%, 5.5%, and 3%, respectively. The dry density of CL soil and calcium bentonite decreased by about 8% and 2%, respectively, with the addition of U.M.O. compared to water. AFM images showed that leachate contamination significantly increased surface roughness, degrading clay surfaces and forming a porous structure.

Source: Results in Engineering

DOI: 10.1016/j.rineng.2025.104541

Authors: Mohamad Bagher Akbari Dangsaraky, Hossein Motaghedi, Saman Soleimani Kutanaei, Nima Ranjbar Malidarreh

Institutions: Islamic Azad University of Ayatollah Amoli, Qaemshahr Islamic Azad University, Islamic Azad University, Tehran

Language: English

Topic: Landfill Environmental Impact Studies

Subfield: Waste Management and Disposal

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation

Open Access status: gold

Estimated APC paid: $1,940