Assessing one-year effects of 10 % pumice powder on strength and microstructure of contaminated clay (Case Study: Ahvaz Project, Iran)

Abstract

Urbanized oil-rich regions, such as Ahvaz, Iran, face significant geotechnical challenges due to widespread oil contamination in soils. This contamination poses a major problem for construction projects, particularly with the increasing installation of oil pipelines within city limits, which exacerbates soil pollution risks. Addressing this challenge, the present study explores an innovative solution using pumice powder (PP), a natural silica-based stabilizer, to improve the long-term geotechnical properties of oil-contaminated fine-grained soils. This research fills a critical knowledge gap by evaluating the effectiveness of PP in stabilizing soils contaminated with varying oil concentrations (4 %, 7 %, and 10 %) and treated with different percentages of PP (5 %, 10 %, and 15 %). The comprehensive investigations in this study included assessments of mechanical properties, durability, microstructural changes through field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and chemical properties using Fourier transform infrared analysis (FTIR). The findings revealed that 10 % PP significantly increased the soil's long-term unconfined compressive strength by up to 370 %, enhanced durability, and reduced susceptibility to cracking, marking a sustainable alternative to environmentally costly traditional stabilizers. This novel use of PP not only fills a crucial knowledge gap concerning the long-term structural integrity and resilience of such soils but also advances the field towards more sustainable and ecologically responsible soil stabilization practices, contributing broadly to environmentally friendly construction methodologies in the oil-rich regions.

Keywords

• Strain energy
• Microstructure
• Oil-rich regions
• Durability
• Stabilization
• Unconfined compressive strength