Experimental study of concrete creep under thermal-mechanical-hydric conditions

In this paper, the creep deformations of two representative concrete materials are investigated under thermal-mechanical-hydric conditions. Both basic and drying creeps are considered. Triaxial compression creep tests are first performed under a confining pressure of 5 MPa and three different values of temperature (T = 20 degrees C, 50 degrees C or 80 degrees C). Two different levels of differential stress are considered (50% and 80% of the peak strength at 20 degrees C). These tests are used for the characterization of basic creep. Then hydric creep tests are conducted on samples subjected to uniaxial compression condition with different prescribed values of axial stress (30%, 50% and 70% of the uniaxial compressive strength) and at constant temperature (20 degrees C). The samples are progressively dried by decreasing the relative humidity (RH) from 98 to 50%. The relative variations of sample mass are also measured during the drying process. It is found that the basic creep strain rate is enhanced by temperature and differential stress. The drying kinetics is strongly influenced by the compositions of concrete. The drying creep deformation is directly correlated with the mass loss kinetics.