Swelling-Induced Shear Failure in Sand-Hydrogel Mixtures: An X-ray CT Study

Abstract Hydrogels have been identified as environmentally friendly and sustainable soil additives for improving soil properties for agricultural and geotechnical engineering purposes. The swelling of hydrogel particles during the wetting process leads to soil restructuring, fundamentally altering the mechanical behaviour of treated soils. This study presents an experimental investigation of the wetting process of sand-hydrogel mixture in triaxial conditions and its impact on shearing behaviour. X-ray tomography is employed to visualize hydrogel swelling and fabric change at particle- and pore-scale. Swelling of hydrogel particles severely affects the soil’s structural rigidity as soil particles are continuously restructured. Eventually, hydrogel swelling induces shear failure under constant deviatoric load and the formation and activation of shear zones.