Hydraulic Conductivity Characteristics of a Clayey Soil Incorporating Recycled Rubber and Glass Granules

Recycled waste materials have been employed to stabilize clayey soil by many practitioners in geotechnical engineering. However, the effects on hydraulic conductivity and its underlying mechanism have rarely been explored. The study aims to examine the hydraulic conductivity characteristics of soil reinforced with the inclusion of selected recycled waste granules, rubber crumb (RC) and crushed glass (CG) under changing confinement. For this purpose, a series of consolidation tests were carried out by varying recycled waste type and additive contents (0%, 5%, 10% and 20% additive content by dry weight of soil). The confining stress was increased within a range of 6.25 kPa to 200 kPa. The results reveal that the addition of RC and CG, as well as the stress state, significantly impacted the soil’s hydraulic conductivity (k). The hydraulic conductivity of both RC/CG soil composites consistently declined with increasing applied stress. Moreover, as the concentration of recycled waste granules in the reinforced soil increased, the hydraulic conductivity value k initially increased, reaching a peak before subsequently declining. Additionally, the study utilized scanning electron microscope (SEM) imaging, which revealed that the inclusion of RC and CG significantly influenced hydraulic conductivity-related parameters by modifying pore size and distribution.