Analysis of artificially structured soil in lightly cemented kaolin

Abstract

This study presents a controlled reconstitution method to develop artificially structured soils focusing on lightly cemented kaolin, aiming to replicate natural clay features for laboratory research. It systematically investigates the influence of light cementation, initial water content, curing time, and specimen orientation. Findings show that even 1% cement content significantly increases the yield stress, confirming soil structuration. Initial water content is a decisive factor, as higher values lead to a more open fabric, characterised by larger initial void ratios and pore sizes. Macrostructure tests reveal a brittle failure mode; strength and stiffness increase with cement and curing time, but decrease with higher initial water content. Anisotropy has only a minor influence on compressibility and mechanical properties, attributed to the low reconstitution pressure and early cement hydration ‘locking in’ a random particle fabric. Microstructural analyses, including SEM, mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD), support these macroscopic observations. SEM images confirm ettringite formation and the progressive filling of inter-aggregate pores with increasing cement. MIP results indicate pore refinement, while XRD analysis indicates a reduction in kaolinite crystallinity due to chemical alteration. This research provides a methodological basis for standardising the preparation of artificially structured soils and advancing the understanding of lightly cemented clay behaviour.

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