Modeling basic creep of concrete since setting time

Modeling the early age evolution of concrete properties is necessary to predict the early age behavior of structures. In case of restrained shrinkage or application of prestress load [1], creep plays an important role in the determination of the effective stress. The difficulty lies in the fact that the modeling of creep must be based on experimental data at early age and this data must be obtained automatically because the hardening process of the concrete takes place rapidly during the first hours and also the first days. This paper presents a new methodology to model basic creep in compression since setting. Two kinds of tests are used: classical loadings and repeated minute-scale-duration loadings. The classical test is used to characterize the creep function for one age at loading and the repeated minute-scale-duration loadings test is used to define two ageing factors for the creep function. A new model based on the physical mechanisms and the two ageing factors is presented. A comparison with the Model Code 2010 is done and an advanced way to consider ageing with the Model Code 2010 is presented.