Editors: | F. Kongoli, E. Aifantis, A. Chan, D. Gawin, N. Khalil, L. Laloui, M. Pastor, F. Pesavento, L. Sanavia |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2019 |
Pages: | 190 pages |
ISBN: | 978-1-989820-06-3 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The prediction of the behavior of cementitious materials and concrete structures under severe conditions and/or for long time spans is of paramount importance in civil, environmental and nuclear engineering. Often, commercial tools do not provide a sufficiently accurate response, so it is necessary to use more sophisticated approaches.
In this work, a general framework for the simulation of the non-linear behavior of concrete is shown and described. It is based on the mechanics of multiphase porous media. The mathematical model is developed by writing the relevant balance equations for the constituents at the pore scale, i.e. the local form of governing equations formulated at micro-scale, and by upscaling these equations to the macroscopic scale, taking into account thermodynamic constraints according to the so-called TCAT (Thermodynamics Constrained Averaging Theory) which assures that all the thermodynamics are properly up scaled from the micro to the macro level. Thanks to this approach, all the relevant quantities involved are thermodynamically correct, no unwanted dissipations are generated, and both the bulk phases and interfaces are taken into account. This procedure does not exclude, however, the use of a numerical multiscale approach in the formulation of the material properties. The numerical solution is obtained directly at the macro level by discretizing the governing equations in their final form.
The resulting model can be usefully applied to several practical cases: evaluation of the concrete's performance at early stages of maturing massive structures [1-3], structural repair works [2,3], exposure of concrete to high temperatures, e.g. during fire [4,5], cementitious materials subject to freezing/thawing cycles [6], etc.
In this work, the general model focuses on the specific situations described above and several examples are shown.