Shear strength of cemented sand in unconfined compression and direct shear tests

Cemented sand, composed of sand and cement, is widely used in geotechnical engineering due to its high strength and stability. While the triaxial compression test (TCT) is a standard method for evaluating shear strength, it can be time-consuming and costly. This study proposes a simplified and cost-effective approach by integrating unconfined compression testing (UCT) with camera vision technology to estimate both compressive and shear strength parameters. Cemented sand samples with 10% cement content were tested using UCT and direct shear tests (DST). A novel camera-based technique was used to measure the failure plane angle in UCT, enabling the estimation of internal friction angle and cohesion. The results show that compressive strength and stiffness are highly sensitive to the void ratio, while internal friction angle remains relatively stable. Cohesion values obtained from UCT closely match those from TCT, confirming the reliability of the proposed method. The integration of camera vision with UCT allows for a more efficient and comprehensive evaluation of material behavior. The method has been validated through comparisons with TCT, DST, and previous studies, demonstrating its accuracy, repeatability, and practical applicability. It holds strong potential for broader use in testing various geomaterials such as soil, cemented sand, and concrete.