Enhancing geotechnical properties of poorly graded soils using crumb rubber and 3-D geogrid reinforcement

Poorly graded soils pose challenges due to their inconsistent particle sizes. Utilizing recycled waste materials in civil engineering applications offers promising benefits in enhancing soil quality and reducing waste generation. Locally available soil was stabilized with varying percentages of crumb rubber in conjunction with biaxial and 3D geogrid reinforcement separately. The aim was to advocate for the use of this combination as an alternative material for improving the geotechnical properties of poorly graded sands. Large-scale direct shear tests were carried out on soil–crumb rubber samples without geogrid, with biaxial geogrid, and with 3D geogrid. The results revealed that incorporating crumb rubber into soil in combination with geogrid reinforcement significantly improves shear strength parameters up to a certain crumb rubber content (by weight). This enhancement in shear strength is attributed to particle inter-locking, apparent cohesion, and frictional resistance arising from incorporating both, crumb rubber and geogrid reinforcement to the soil specimen and this not only enhances the geotechnical properties but also reduces reinforcement costs, contributing to a sustainable solution that mitigates the detrimental environmental impacts of waste rubber disposal.