Dam concrete in situ creep tests. Experimental setup and results from six large concrete dams

Abstract

This paper describes the main features of the experimental in situ setups used to estimate the concrete deformability from six large Portuguese dams, all of which were built in the last 25 years. These experimental setups are commonly referred to as creep cells and aim at determining the modulus of elasticity for different ages and estimating the creep curve, under the same thermo-hygrometric conditions as the dam. Creep cells are composed of specimens of concrete with embedded strainmeters, placed in the body of a concrete dam during its construction, with a hydraulic flat-jack underneath. During the elastic modulus and the creep tests, while the jack introduces a given compressive stress in the specimen, the embedded strainmeters measure the sub-sequent strains, instantly or over time, for the modulus of elasticity or creep assessment, respectively. In recent years, there have been several developments in the design and in the instal-lation methodology of this type of experimental setup, namely in Alqueva, Baixo Sabor, Ribeiradio, Foz Tua, Daivões and Alto Tâmega dams. The article also presents a brief compilation of the most important creep cells results for these dams, which are being used as an input to numerically evaluate the structure’s behaviour over time.