Assessment of the geotechnical and microstructural characteristics of lime stabilised expansive soil with bagasse ash

Bagasse ash is a readily available waste by-product of the sugar-cane refining industry; its improper disposal can cause adverse environmental impacts. Therefore, bagasse ash is considered in this assessment to investigate the possibility of utilising it as an additive for stabilisation of expansive soils. This study aims to assess the improvement in geotechnical properties of expansive soil stabilised with various contents of bagasse ash and lime. The geotechnical characteristics of stabilised soil were examined through a series of unconfined compressive strength (UCS) tests of untreated and treated soil specimens for various curing periods of 3, 7, 28, and 56 days. A preliminary study on the microstructure development of untreated and treated soils was also conducted using scanning electron microscopy (SEM) technique. The results of the UCS tests reveal that the additions of hydrated lime alone, and combined hydrated lime-bagasse ash improved the compressive strength and the stiffness of stabilised soil remarkably. The significant strength development of lime treated soils with bagasse ash was observed not only at the initial stage of 28 days of curing but also at the subsequent 28 days irrespective of additive content. However, for soil samples treated with hydrated lime alone, the predominant strength gain was obtained at the initial stage of 28 days of curing. Subsequently, the compressive strength remained almost constant when curing time exceeded 28 days. The outcomes of the SEM analysis indicate the change in microstructure of the stabilised soils and the formation of new cementitious compounds of Calcium-Silicate-Hydrate (C-S-H). The findings of this study reveal that the application of hydrated lime and bagasse ash combination, as reinforcing construction materials, enhances the geotechnical properties of expansive soil. Using bagasse ash combined with lime can address the coming environmental impacts of bagasse ash disposal, while providing cost-effective and alternative construction materials for sustainable infrastructure development