4. Simulation based modelling of time- and shear-dependent disperse and rheological properties of cement suspensions

Principal investigator(s) - PI

Researcher(s) in-charge- RI

Former Members

  • M.Sc. Dimitri Ivanov
    Technische Universität Braunschweig, Institut für Partikeltechnik (iPAT)
  • Prof. Dr.-Ing. Hans-W. Krauss
    Technische Universität Braunschweig, Institut für Baustoffe, Massivbau und Brandschutz (iBMB), Fachgebiet Baustoffe
  • Prof. Dr.-Ing. Arno Kwade
    Technische Universität Braunschweig, Institut für Partikeltechnik (iPAT)
  • Prof. Dr.-Ing. Dirk Lowke
    Technische Universität Braunschweig, Institut für Baustoffe, Massivbau und Brandschutz (iBMB), Fachgebiet Baustoffe
  • M.Sc. Mahmoud Eslami Pirharati
    Technische Universität Braunschweig, Institut für Baustoffe, Massivbau und Brandschutz (iBMB), Fachgebiet Baustoffe
  • Prof. Dr.-Ing. Carsten Schilde
    Technische Universität Braunschweig, Institut für Partikeltechnik (iPAT)

Subject Area

Construction Material Sciences, Rheology of Cementitious Materials, CFD-DEM Simulations

Term

11.2017-11.2020

Project Identifier

Deutsche Forschungsgemeinschaft (DFG) – Projekt number 387066140

Project Description

The aim of the project is to develop enhanced constitutive models for the prediction of rheological properties of cementitious materials based on chemical and physical particle and fluid characteristics. Bridging the gap between fundamental insights into chemical and physical processes at nano as well as micro scale and the macroscopic flow behavior, the project contributes for overcoming limitations of existing constitutive rheological models. Thereby, a more reliable simulation and modelling of concrete flow even for complex processing steps with time-variant shear history, such as pumping, 3D printing or spraying, is enabled. To that end, the time- and shear-dependent disperse and rheological properties of cementitious suspensions are investigated and modelled based on fundamental material properties and interactions with the help of coupled CFD-DEM simulations. With the help of the simulations, the basic interactions depending on numerous chemical and physical particles and fluid characteristics, mixture composition and processing parameters will be modelled comprehensively. New time-dependent contact models are developed and used for the coupled CFD-DEM simulations. The results of the simulation environment are calibrated and validated by different experiments. The properties of particles and fluid relevant for the simulations are investigated in cooperation with other working groups using different reacting and non-reacting technical and model particulate systems. The disperse and rheological properties of the suspensions are characterized comprehensively. Relevant particle and fluid characteristics are investigated by rotational rheometer tests. The microstructure effect on the rheological properties is described. Therefore, the agglomeration state and the rheological properties are characterized for different shear rates, time steps and shear histories with and without regard for hydration effects. Moreover, the particle size distribution and the agglomeration state of the pastes are determined under shear conditions by a laser backscattering method integrated into a new coaxial cylinders rheometer setup. Based on the simulation and experimental results the time- and shear-dependent microstructure effects are implemented into existing constitutive models enabling the consideration of thixotropic effects and ageing effects due to cement hydration. Being a key parameter for constitutive models and multi-scale modelling, a special focus will be on the determination of local shear rates acting on the paste phase. The approach will enable capturing realistic shear parameters for the simulations and experiments at micro scale, hence allowing a more reliable scale-up and modelling.

Schematic overview of the experimental and simulation work planned within the project
© Technische Universität Braunschweig

Publications

  1. Ivanov, D.; Becker, S.; Lu, Z.; Eslami Pirharati, M.; Kwade, A.; Krauss, H.-W.; Stephan, D.; von Klitzing, R; Schilde, C., Synthesis and Analysis of Spherical Cementitious Model Particles, in: Rheol. Process. Constr. Mater. RILEM Bookseries B. Ser., RILEM Bookseries: Springer, Cham, Switzerland, 2020: pp. 602-609
  2. Eslami Pirharati, M.; Ivanov, D.; Krauss, H.-W.; Schilde, C.; Lowke, D., Numerical Simulation of the Flow Behavior of Newtonian Fluids in a Wide Gap Rheometer by CFD, in: Rheol. Process. Constr. Mater. RILEM Bookseries B. Ser., RILEM Bookseries: Springer, Cham, Switzerland, 2020: pp. 588-595
  3. Eslami Pirharati, M.; Krauss, H.-W.; Schilde, C.; Lowke, D., Effect of Different Shear Rates on Particle Microstructure of Cementitious Materials in a Wide Gap Vane-in-cup Rheometer, Materials (Basel). 13 (2020)
  4. Haist, J. Link, D. Nicia, S. Leinitz, C. Baumert, T. von Bronk, D. Cotardo, M. Eslami Pirharati, S. Fataei, H. Garrecht, C. Gehlen, I. Hauschildt, S. Ivanova, I. Jesinghausen, C. Klein, H.-W. Krauss, L. Lohaus, D. Lowke, O. Mazanec, S. Pawelczyk, U. Pott, J.J. Radebe, N. W. Riedmiller, H.-J. Schmid, W. Schmidt, E. Secrieru, D. Stephan, M. Thiedeitz, V. Wilhelm, M. Mechtcherine, Interlaboratory study on rheological properties of cement pastes and reference substances – Comparability of measurements performed with different rheometers and measurement geometries, Mater. Struct. 53 (2020)
  5. Z. Lu, M. Haist, D. Ivanov, C. Jakob, D. Jansen, P.A. Kißling S. Leinitz, J. Link, V. Mechtcherine, J. Neubauer, J. Plank, W. Schmidt, C. Schilde, C. Schröfl, T. Sowoidnich, D. Stephan: Characterization data of reference cement CEM III/A 42.5 N used for Priority Program DFG SPP 2005 “Opus Fluidum Futurum – Rheology of reactive, multiscale, multiphase construction materials”, Data in Brief. 30 (2020). doi:10.1016/j.dib.2019.104699
  6. Z. Lu, M. Haist, D. Ivanov, C. Jakob, D. Jansen, S. Leinitz, J. Link, V. Mechtcherine, J. Neubauer, J. Plank, W. Schmidt, C. Schilde, C. Schröfl, T. Sowoidnich, D. Stephan “Characterization data of reference cement CEM I 42.5 R used for priority program DFG SPP 2005 Opus Fluidum Futurum Rheology of reactive, multiscale, multiphase construction materials”, Data in brief 27 (2019)