Microscopic analysis and image processing for quantifying particle shape in geotechnical engineering

Particle shape is a significant factor influencing soil’s engineering behavior, affecting permeability, packing density, dilatancy, and shear strength. Angularity, a key element of particle morphology, provides insights into the transport history of sedimentary deposits. Current soil classification methods, such as those in the USCS and AASHTO systems, largely rely on sieve analysis, Atterberg limits, and hydrometer analysis. By neglecting particle shape, these methods can lead to inconsistencies in soil classification. Incorporating particle shape quantification, however, faces challenges, primarily the lack of accessible, cost-effective, and standardized measurement techniques. This study addresses this gap by quantifying the grain shape characteristics of granular soil samples collected from Addis Zemen town, Abay desert, and Lalibela town in Ethiopia. High-quality grain images were captured using microscopic imaging and analyzed using ImageJ software to determine roundness, circularity, and aspect ratio. The analysis revealed variations in roundness, with Abay sand exhibiting the highest value (0.78), followed by Addis Zemen sand (0.71) and Lalibela sand (0.69). This work contributes to a better understanding of soil properties in these regions and provides a basis for integrating particle shape into soil classification practices.