Swelling characteristics of compacted graphene-modified GMZ bentonite infiltrated with NaCl solution

Graphene is regarded as a promising additive to enhance the thermal conductivity of bentonite in the geological repository, yet the hydro-mechanical properties of its mixture with bentonite under chemical conditions remain unclear. This work examined the one-dimensional swelling deformation of high-density graphene-modified bentonite (GMB) in NaCl solutions, considering the influences of graphene content and NaCl concentration. Results indicate that both graphene and NaCl reduced the maximum swelling strain and the primary and secondary swelling coefficients of GMB. Additionally, graphene enhanced the stability of swelling deformation in bentonite across various NaCl concentrations and decreased the GMB’s test duration. The relationship between test duration and NaCl concentration was nonmonotonic. The ratio of swelling strain at each stage to total swelling strain was rarely affected by graphene content or NaCl solution. Scanning electron microscope examinations on selected samples post-swelling tests unveiled a unique soil structure in GMB. Furthermore, a model was put forward to predict the maximum swelling strain of GMB inundated in NaCl solutions, and its feasibility was verified.