Direct Shear Box Assessment of Sand–Rubber Mixtures: Strength, Ductility, and a Performance Index

Authors : Şahin Çağlar Tuna

Pages : 977-991

Doi:10.21605/cukurovaumfd.1796691

View : 41 | Download : 60

Publication Date : 2025-12-29

Article Type : Research Paper

Abstract :The reuse of waste materials in geotechnical engineering promotes sustainability while enhancing soil performance. This study investigates the effect of shredded waste rubber on sand through consolidated drained direct shear tests at two relative densities (Dr ≈ 30% and 70%) with 0–10% rubber content. Rubber inclusion reduced brittleness and improved ductility, with mixtures containing 2.5–5% achieving the most favorable strength–deformation balance. In loose sand, cohesion and friction angle increased up to 5%, while in dense sand cohesion rose slightly but friction angle declined at higher contents. A new Performance Index (PI) is proposed in this study, integrating energy absorption, ductility, and residual-to-peak strength into a unified framework. The PI confirmed the 2.5–5% range as optimum, providing a practical tool for mixture evaluation. These findings indicate that low rubber contents are suitable for seismic embankments, retaining walls, and transportation subgrades, while higher contents may be more effective in lightweight and energy-dissipative applications.
Keywords : Kum–lastik karışımı, Kesme mukavemeti, Kohezyon, İçsel sürtünme açısı, Süneklik, Performans İndeksi, Sürdürülebilir geoteknik, Atık lastikler

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