Engineering and Leaching Behavior of Lime-Treated Fly Ash Amended with Montmorillonite Nanoclay

Abstract

Researchers have explored the utilization of nanoparticles to improve the properties of soils for various geotechnical construction applications. However, the potential of nanoparticles and their mechanisms of action in enhancing the behavior of industrial byproduct pozzolanic materials has not been properly examined. Hence, in the present study, we aimed to investigate and optimize montmorillonite nanoclay (m-NC) content to improve the engineering properties (unconfined compressive strength, compressibility and permeability) of fly ash with and without lime treatment. In addition, we examined the leaching potential of metal ions through m-NC amended with untreated and lime-treated fly ash by performing leachate column and inductively coupled plasma mass spectrometry (ICP-MS) tests. The mechanisms of change in the engineering properties of lime-treated fly ash with m-NC were uncovered through several microlevel investigations. The results revealed that the strength of untreated and lime-treated fly ash was enhanced significantly with the addition of m-NC. Furthermore, the addition of m-NC to fly ash led to increased compressibility but in same time, it reduces for lime-treated fly ash. However, the permeability of untreated and lime-treated fly ash decreased with the addition of m-NC. The leaching potential of metal ions decreased significantly with the addition m-NC to fly ash. Microlevel investigations confirmed the plate-like fine particles having higher specific surface area of m-NC, improvement in gradation with filling of voids and acceleration in pozzolanic reactivity and thereby formation of silicate and aluminate hydrated cementitious compounds are the key factors in controlling the behavior of lime-treated fly ash with m-NC content.