Investigation of rubber content and size on dynamic properties of expansive soil–rubber

Waste rubber has been widely applied in geotechnical engineering, benefiting from its light weight, high elasticity, low density, good durability and high compressibility. In this paper, the effects of rubber content (RC) and rubber size (d₀) on the dynamic properties of expansive soil–rubber (ESR) were investigated by low-temperature dynamic triaxial tests. The results show that: (1) the shear stress of ESR decreases with the increase of RC with a particle size ratio of 1.3, but first decreases and then increases with a particle size ratio of 2.4; (2) the RC threshold between soil-like and rubber-like ESR is 10%; (3) the maximum shear modulus ratio of ESR occurs at RC = 10% and d₀ = 0.25 mm, with the best dynamic performance; (4) the hysteretic curve of ESR was flat and elliptical, deviating upward to the right at freezing condition. In addition, different contact modes between rubber and expansive soil are proposed and the contact mechanism has been revealed.