Horizontal construction joints parameters

摘要

The Roller Compacted Concrete (RCC) construction method creates several horizontal construction joints. The joints are a result of layer's thickness usually from 0.25 m to 0.50m. The RCC construction method has many more horizontal construction joints than conventional concrete, and has the possibility of a very fast volume placement. These facts allied to the necessity of a very dry concrete raise doubts about the joint characterization parameters since the beginning of the use of RCC as a valid concrete construction process. Several design of concrete dams criteria need the characterization of cohesion, shear friction angle, compressive strength and tensile strength. To achieve a trustable result according to safety analysis, several solutions have been used as conventional concrete bedding mixes, mortar between layers and surface treatment, or a combination of various construction actions. All these treatments include the analysis of weather conditions, construction methods and time interval between layers construction. The use of sloped layer construction process turns the time interval between construction joints very short, generating much more care in the study of time influence. This paper shows results of a research proposed to analyze the joints parameters using laboratory test fills performed in a device prepared to simulate several site and equipment conditions in the FURNAS RCC Laboratory in Goiania, Brazil. The research includes time interval between layers, horizontal joints treatments, bedding mixes, and weather conditions. The device has been calibrated using comparisons of results obtained in laboratory with those obtained during construction. The paper analyzes various test proceedings, evaluating sample size and boundary conditions.