One-Dimensional Compression Response of Sands Amended with Fly Ash Related to Particle Morphology Effects

The primary goal of this study was to investigate the influence of particle morphology characteristics on the compressibility behavior of sandy soils, an aspect that remains insufficiently explored in existing geotechnical literature. Although particle morphology plays a fundamental role in soil mechanics, there is a notable lack of comprehensive data and analysis to thoroughly understand the underlying mechanisms that control these interactions. To address this knowledge gap, the study implemented a detailed experimental program, which involved performing a series of one-dimensional compression tests on three distinct sand types, each representing different particle shapes: dune sand “rounded”, Chlef sand “sub-rounded”, and quarry sand “angular”. The sands were treated with four different fly ash content levels: 0%, 5%, 10%, and 15%. This incremental addition was designed to provide a comprehensive understanding of how varying proportions of fly ash influence soil compressibility, considering both size and shape characteristics of the sand grains. The experimental data revealed a pronounced correlation between the coefficient of compressibility of the sand-fly ash mixtures with particle morphology. Strong correlations were established between compressibility and the different sand types, highlighting the impact of particle angularity on soil behavior under compression. Additionally, the incorporation of fly ash powder significantly improved the compressibility characteristics of the sandy soils. This incremental addition was designed to provide a comprehensive understanding of how varying proportions of fly ash influence soil compressibility, considering both size characteristics (including effective grain size, mean grain size and coefficient of uniformity) and shape characteristics (including sphericity, Roundness and Overall regularity) of the sand grains. Notably, as the fly ash content increased, the compressibility of the sand mixtures decreased. This study contributes valuable insights into the complex interactions between particle morphology, soil composition, and compressibility, thereby advancing the understanding of soil behavior in geotechnical engineering applications.