Juan Pablo Gallo Molina
Prof. dr. ir. Ingmar Nopens - Ghent University
Dr. ir. Karel Lesage - Ghent University
Concrete is the most produced material in the world and hence it has a critical importance for the economy and environment. For hardened concrete, civil engineers already possess a series of engineering tools that allow them to satisfactorily predict properties of interest as a function of material characteristics. However, when this material is encountered in a fluid state, the picture is completely different: only some empirical tests are capable of relating some material variables (e.g. concrete composition) with relevant properties (i.e. flow speed, flow spread, etc.). Although this practice is longstanding, the increasing complexity of concrete mixtures - introduced by the growing use of mineral additions, chemical admixtures and non-traditional cement chemistries - has invoked the need for developing mechanistic models with predictive capabilities.
The study aims to contribute to alleviate the existing lack of appropriate modelling tools for fresh concrete. As the rheology of fresh concrete impacts the final properties of the hardened material and, in turn, the aggregate size distributions and their transient behavior affects the rheology, the use of Population Balance Models has been deemed a necessary step for the adequate modelling of fluid concrete. Considering that the size range of the particles found in a typical concrete can encompass several orders of magnitude -which implies that numerous kinds of interactions and phenomena are involved-, a bottom-up modelling approach is often aimed for in the modelling of these systems. For this reason, this study will focus on cement pastes. An adequate Population Balance Model will formulated and calibrated with experimental data. The relevant hydration reactions will be taken into account. These models will be subsequently coupled with rheological models with the goal of developing a tool capable of describing the flow of fresh cement as a function of its composition.