Improving Engineering Properties of Soil for Highways Purposes by Halloysite Nanotubes

Abstract

This study investigates the stabilizing effects of Halloysite nanotubes on the geotechnical features of gypseous soil as a subgrade. The soil that was utilized for this study was collected from Ayn al-Tamr in Karbala City, southwest of Iraq, having an average gypsum of 30% and was designated as (SP) by (USCS). As a percentage of the dry unit weight of the soil, the gypseous soil was mixed with a small amount of nanomaterial (Halloysite nanotubes). A set of physical and chemical identification tests have been conducted on the original soil, as well as additive, direct shear, collapsibility, and California bearing ratio (CBR) testing on both untreated and treated soil samples using Halloysite nanotubes. Three different additive proportions (2.5, 5, and 7.5) % by dry unit weight of soil were added to soil samples. The results of the conducted tests revealed that the geotechnical properties of the soil sample were considerably modified. As the amount of utilized nanomaterials increases, the collapse potential instantly decreases. In addition, soil strength and stability were increased by increasing CBR values, and the collapse severity was changed from moderate trouble to no problem. Thus, the value of 2.5% of Halloysite nanotubes can be considered as an optimum percentage based on the results of the mentioned tests.

Keywords

• halloysite nanotubes
• soil stabilization
• gypseous soils
• subgrade
• engineering properties