A macro-meso chemo-physical analysis of early-age concrete based on a fixed hydration model

This work employs a finite-element analysis of a chemo-thermal coupled concrete model that is clearly distinguishable from other models in the existing literature. Finite-element simulations are performed on both a macro-and mesoscale, with a mesoscopic mesh of random polygons generated by a Monte Carlo method. In order to link the two scales and identify their differences, a multi-scale framework based on a homogenisation scheme is adopted in the parameter studies. Macroscopic simulations are run on concrete samples with various water-cement ratios, and the outcomes are compared to experimental temperature curves, which show that the hydration model provides a relatively high accuracy. Mesoscopic thermo-chemical behaviours are accurately predicted for concrete samples with various volume fractions and aggregate compositions. The results show that the cooling conditions and the aggregate volume fraction and composition play a significant role in the chemo-physical process. The inhomogeneous distribution of hydration degree caused by the coarse aggregates in the concrete may lead to the presence of temperature gradients and slow the growth of cement strength, particularly in the areas where aggregates are concentrated.