Micromechanics-based multifield framework for early-age concrete

In the process of hydration of concrete, there are considerable interacting physical and chemical changes inside the material, affecting both composition and morphology of concrete at early ages. These changes are properly considered within multiscale models comprising several scales of observation and giving access to the effective properties via upscaling. In this paper, a multiscale model for early-age concrete is implemented into a multifield (thermo–hygro–chemo–mechanical) framework, which accounts for all major processes among the solid, liquid, and gas phases of concrete by means of mass, energy, and momentum equilibrium. The proposed modeling approach is employed for the investigation of the effect of formwork removal (stripping) of early-age concrete, exposing the concrete surface to the outside environment which may cause early-age cracking of concrete structures. Based on the multiscale approach, the authors evaluate the cracking risk of concrete members with respect to the underlying mix-design, size of the concrete member, and stripping time, providing first insight into the influence of these parameters on the cracking risk of early-age concrete.