Investigation of the Mechanical Properties and Failure Modes of Single Calcareous Sand Particles and Artificially Cemented Particles

Calcareous sands present significant geotechnical challenges because of their complex particle shapes, porous microstructures, and low particle strength. This study investigates the micromechanical properties and failure modes of these sands to enhance understanding critical for engineering applications. Uniaxial compression tests were performed on single calcareous sand particles to assess the effects of particle shape and size on their mechanical behavior. The results classified the force–displacement curves of single particles into three modes—hardening, softening, and flattening—predominantly influenced by particle morphology. Additionally, artificially cemented calcareous sand particles were subjected to tensile, compression, pure shear, and compression–shear-bending tests using a novel apparatus. The artificially cemented calcareous sands showed higher peak tensile strength and greater deformation than cemented quartz sands. Compression tests revealed two failure modes, which is associated with peak strength and particle crushing. In the combined compression–shear-bending tests, greater normal pressure enhances the sample’s resistance to bending and shear. The findings highlight that particle shape, size, and cementation significantly affect the mechanical behavior of calcareous sands, providing valuable insights for improving design practices and mitigating risks in projects.