Mechanical Behaviour of Nano-material (Al2O3) Stabilized Soft Soil

Rapid urbanization and requirement of infrastructure, stable construction sites are not available. Therefore, there is a dire need for improvement of marginal soils to be used as a construction material. However, weak soils comprise of saturated clays, fine silts, and loose sand, which are susceptible to failure and pose problems of stability. Therefore, this research aims to study the strength and microstructural behavior of soft soils treated with nano-alumina (Al2O3) additive. In this study, Al2O3 of different percentages (0.5, 1.0, 1.5, and 2.0%) by dry weight of soil was added to a clayey soil and subjected to compaction and unconfined compression strength tests. The compaction tests showed that nano-Al2O3 (< 2.0%) stabilized soils exhibit higher unit weight and lower water content compared to untreated soils. This may be attributed due to the fact that nano-materials possess higher unit weight compared to untreated soils and these materials occupy the pore spaces in-between the soil grains, which reduce soil porosity and increase the shear strength. The unconfined compressive strength test on cured treated soil specimens showed a significant increase in shear strength on the addition of nano-alumina. The scanning electron microscopic analysis on untreated and treated soil specimens showed that untreated soil samples exhibit a compact array of clay grains and nano-material treated soil display closely packed and condensed fine structure, which authenticates an increase in shear strength. Thus, with the addition of Al2O3, there has been a significant improvement in the engineering properties of soft soils.