Lime Stabilization of Soils: Reappraisal

TLDR

Lime generally improves soil performance, but some cases report adverse effects. The study aims to understand lime stabilization mechanisms across diverse soil plasticity and mineralogy. Six soils, including montmorillonite‑rich expansive and silica‑rich non‑expansive types, were reconstituted and lime effects assessed through liquid limit, plastic limit, swell, compressive strength, mineralogy, and microstructure. An optimum lime content exists beyond which strength gains decline, particularly in silica‑rich soils where silica gel formation creates porous, water‑retentive gels that reduce strength and increase plasticity, so excessive lime should be avoided.

Abstract

Lime generally improves the performance of soils. However, some cases reported an adverse effect. To develop an understanding of the underlying mechanisms, a systematic study covering a wide range of plasticity and mineralogy of soils was carried out. Six different soil samples were reconstituted using two extreme types of soils, in other words, a montmorillonite rich expansive soil and a silica-rich non-expansive soil. The influence of lime stabilization on these soils was evaluated through determination of geotechnical properties such as liquid limit, plastic limit, swell, compressive strength, mineralogy, and microstructure. An optimum lime content beyond which the strength improvement decreased was found. This phenomenon is more prominently observed with silica-rich soils that form silica gel. As the silica gel is highly porous, when formed in large scale the strength gain from cementation is substantially countered by the strength loss from gel pores, giving rise to a visible reduction in overall strength. Additionally, the gel materials hold a large amount of water, leading to increased plasticity and swelling. Therefore, excessive lime treatment should be avoided for silica-rich soils.