International Journal of Civil & Structural Engineering
Author(s) : J. O. MORANDI, R. J. ULIARTE
Roller Compacted Concrete (RCC) Dam construction involves the placement of concrete in successive layers, whose thickness may vary in general between 30 and 45cm. The surfaces of contact between layers are planes or joints of potential weakness for the material, giving the same anisotropic mechanical characteristics. The tensile strength and shear strength of the joint between layers are basic design parameters for the RCC dam project, particularly necessary to ensure the reliability of the structure against seismic loads. The present work describes a test method to determine the direct tensile strength of the joint between layers and experimental results are obtained with this method, corresponding to the test of joints made under different conditions of concreting.The conditions studied included the test of joints with and without cement mortar, made with different waiting times between layers. Waiting times were one minute (continuous concreting condition), 6, 12, 24 and 72 hours. In the case of concreting with no waiting time, the results are compared with the indirect tensile strength determined by diametral compression tests. The results allow to confirm the reliability of the method and provide experimental information that shows the influence of the waiting time between layers, or maturity of the joint, in the tensile strength of the joint.