Laboratory Study of Shear and Compressive Strength of Construction Joints in two Ways Categorization Maturity Factor and Time of Setting in RCC Dams

摘要

In RCC dams,different layers are executed with the thickness of 30 to 35 cm according to bulk of sources,available facilities,methods of execution,providing and assuring density of the RCC.The execution of RCC especially in hydraulic structures should be done in a way that the executed structure have consonant blocks for the intended goals.It is clear that the characteristics and the conditions of boundaries between layers is the most effective parameter in determining the boundaries between layers.Although this kind of execution causes higher speed in execution in comparison of usual concrete dams,and it also reduces problems of voluminous concrete placing in sites significantly but the stability of dams against side forces because of relative weakness in shear strength between layers in the place of joints needs especial attention and it is one of the important factors that is important to dam designers.According to technical codes in RCC dams,joints are categorized into four groups,hot,warm,cold,and very cold.Necessary works are done according to the kinds of joint.The standard to define these joints is the amounts of maturity factor which is the product of temperature of the surface of the concrete and time based on Fahrenheit that will be defined after the experimental study and defining time.It seems that this definition is too broad and the most important problem of it is,not mentioning the time of setting of concrete in calculation which is the important factor in determining time span for any kind of joints.In this artical the researcher tries to propose ways to proof the subject according to codes and to find new ways to categorize these joints to promote shear and compressive strength in the place of joints in real conditions.