Thermodynamic modelling: state of knowledge and challenges

Over recent decades, understanding of the fundamental aspects of the chemistry of cement has advanced. Many of the leading-edge contributions on the subject were either authored by Professor Glasser and his colleagues or heavily inspired by their work. In the present paper, the limits and recent evolutions of thermodynamic models applied to cement systems are briefly presented, and their current limitations and future challenges are discussed. A number of examples illustrate how such models can be used to predict the influence of different factors such as cement composition, hydration, relative humidity or temperature on the composition and the properties of a hydrated cementitious system. The combination of chemical and transport models makes it possible to calculate the interactions of cementitious systems with the environment. However, precipitation and dissolution processes can be slow so that thermodynamic equilibrium may not always be reached, particularly during the first stages of the hydration process. This is why an approach that couples thermodynamics and kinetics could provide useful information. The introduction of kinetics would not only help understanding of the intricate influence of various factors, such as solution concentrations, on the hydration of cement but it would also provide the theoretical basis for the development of fully coupled thermo-poro-mechanical models for the prediction of the volume stability of cement systems exposed to chemically aggressive environments.