Numerical modeling of hydration process and temperature evolution in early age concrete

Heat production induced by the hydration reaction and the resulting temperature evolution in the early phases of setting and hardening processes are critical phenomena, often leading to premature cracking of concrete members. However, the interest for simulating such phenomena is also related to the fundamental relationships between the nature of the main concrete components, such as aggregates and binders, and its mechanical properties. As a matter of principle, the actual efficiency of the concrete mix can be assessed by monitoring the hydration process and the latter can be directly related to the development of the relevant mechanical properties. This paper presents a numerical model for simulating the hydration process of cement and the resulting time evolution of temperature inside concrete. In general, boundary conditions ranging between isothermal and adiabatic situations can be considered. Then, the heat-flow generated throughout the hardening concrete specimen as a result of these general boundary conditions can be simulated by the proposed model with the aim to analyze its effect on the cement hydration process and the resulting concrete maturity. After the analytical formulation of the hydration and heat transfer problems, a consistent numerical solution based on the Finite Difference (FD) technique is developed. Then, the same constitutive relationships are considered within a general Finite Element (FE) procedure. The numerical results obtained through FD and FE solutions are compared with the experimental results obtained from two concrete mixes in both adiabatic and non-adiabatic conditions. The comparison between the two numerical predictions and the corresponding experimental results confirms the accuracy of the proposed model. The FD numerical solution can be easily implemented in a spreadsheet