Dynamic shear modulus and damping ratio of clay mixed with waste rubber using cyclic triaxial apparatus

Abstract

Abstract In view of its appropriate engineering properties and environmental benefits, waste rubber is being increasingly used in engineering applications. Along with static loading, clay-rubber mixture (CRM) can be also utilized under dynamic loading. Due to a lack of detailed research on dynamic and static properties of CRMs, the effects of 0–30% rubber content on geotechnical properties of clay soil (CS) was investigated in this study through strain-controlled monotonic and cyclic triaxial tests. Moreover, the structure of the CRM and pure rubber was observed under a binocular microscope. The results indicated the effects of rubber size, rubber content, and shear strain amplitude on strength, volumetric strain, damping ratio, and shear modulus of the CRM. The results correspondingly demonstrated a good cohesion between clay and rubber grains as well as an appropriate strength and shear strain for the given mixture. According to the results of the dynamic tests, the highest damping ratio was obtained with 10% rubber content. In addition, the shear modulus showed a downward trend as the rubber content and the shear strain amplitude augmented. The use of rubber powder rather than granular rubber also enhanced the damping ratio by 10% on average. In contrast, the granular rubber boosted the shear modulus by 13% as compared with the rubber powder. Based on the results, it is recommended to use 10% rubber powder in executive operations to achieve the highest damping ratio. Considering the static strength of the CRM and its good damping ratio under cyclic loading compared with pure soil, it is suggested to be used in situations wherein soil could be subjected to low compressive loads combined with cyclic loading.