Calibration and validation of a numerical model for early age damage analysis

A model for early age concrete mechanical behavior and deformations, which makes use of the microplane model M4 and the solidification-microprestress theory, is presented. The viscoelastic behavior is described according to (1) the solidification theory, in which short-term aging and partially recoverable creep deformations are modelled through a solidification process assumed to be a function of the degrees of hydration and silica-fume reaction and (2) the microprestress theory that models long-term concrete aging and irrecoverable creep deformations. Cracking and nonlinear behavior are modeled by using a modified version of microplane model M4 which is extended to include a realistic aging model. Numerical examples, which deal with the analysis of concrete specimens, both in adiabatic and isothermal conditions, and loaded at different ages, are presented in order to show (1) the calibration procedure of model parameters and, after that, (2) the validation of the model for early age behavior of concrete without any further change of the parameters.