Size effects on creep of unsaturated mine waste rock

In the long term, high mine waste rock piles are subjected to variable environmental conditions which have an impact on their time-dependent deformation. In order to characterize the compressibility, small-scale samples are usually tested. However, the results are affected by size effects due to particle crushing. Whereas previous studies have demonstrated that coarser samples show higher compressibility, the inϐluence of size effects on time-dependent deformation is still poorly understood. The main objective of this paper is to identify the effects of particle size and suction on time-dependent deformation of unsaturated mine waste rock. We carried-out large and standard-sized oedometric compression tests on parallel graded samples. Results show that the coarser the material, the higher the amount of grain crushing, which is reϐlected in a larger compressibility. More interestingly, this paper present for the ϐirst time experimental evidence of size effects on creep strains, which signiϐicantly increase with particle size.