Modelling degradation processes of cement-based materials by means of mechanics of multi-phase porous media

A general approach [1] to modelling various degradation processes in cementitious materials, due to combined action of variable hygral, thermal, chemical and mechanical loads, will be presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose. Kinetics of physico-chemical processes, like for example: cement hydration [2,3], salt crystallization/dissolution [4], calcium leaching [5], Alkali Silica Reaction (ASR) [6], and water freezing/thawing [7], is described with evolution equations based on thermodynamics of chemical reactions. The mass-, energy- and momentum balances, the evolution equations describing chemical reactions and deterioration processes, as well as the constitutive and physical relations will be presented. The mutual couplings between the chemical, hygral, thermal and mechanical processes will be discussed, both from the viewpoint of physicochemical mechanisms and mathematical modelling. Numerical methods used for solution of the model governing equations will be presented. For this purpose the finite element method is applied for space discretization and the finite difference method for integration in the time domain.
Several examples of the model application for analysing transient chemo-hygro-thermo-mechanical processes in cementitious materials will be solved and discussed. The first example deals with concreting and maturing of massive structure. The second example concerns calcium leaching from a concrete wall due to chemical attack of pure water, exposed to gradients of both temperature and pressure. The third one describes cracking of concrete element, caused by development of expanding products of ASR. The fourth example concerns the salt crystallization during drying of a wall made of concrete/ceramic brick, causing degradation of a surface layer due to development of crystallization pressure. The last example concerns freezing and thawing of a wet concrete wall in variable temperature and relative humidity, causing frost damage.
REFERENCES
[1] D. Gawin, M. Koniorczyk and F. Pesavento, “Modelling of hydro-thermo-chemo-mechanical phenomena in building materials”, Bulletin of The Polish Academy of Sciences: Technical Sciences, Vol. 61(1), 51-63, (2013).
[2] D. Gawin, F. Pesavento, B.A. Schrefler, Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. Part I: Hydration and hygro-thermal phenomena, Int. J. Num. Meth. Engng, Vol. 67, No. 3, 299-331 (2006)
[3] D. Gawin, F. Pesavento, B.A. Schrefler, Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. Part II: Shrinkage and creep of concrete, Int. J. Num. Meth. Engng, Vol. 67, No. 3, 332-363 (2006)
[4] M. Koniorczyk, D. Gawin, “Modelling of salt crystallization in building materials with microstructure - poromechanical approach”, Construction and Building Materials, Vol. 36, 860-873 (2012).
[5] D. Gawin, F. Pesavento and B.A. Schrefler, “Modeling deterioration of cementitious materials exposed to calcium leaching in non-isothermal conditions”, Computer Methods in Applied Mechanics and Engineering, Vol. 198(37-40), 3051-3083, (2009).
[6] F. Pesavento, D. Gawin D., M. Wyrzykowski, B.A. Schrefler and L. Simoni, “Modeling alkali-silica reaction in non-isothermal, partially saturated cement based materials”, Computer Methods in Applied Mechanics and Engineering, Vol. 225-228, 95-115, (2012).
[7] Koniorczyk M., Gawin D., Schrefler B.A., Modelling evolution of frost damage in fully saturated porous materials exposed to variable hygro-thermal conditions, Computer Methods in Applied Mechanics and Engineering, Vol. 297, 38-61 (2015).

Short Bio : Prof. Dariusz Gawin got his Ph.D. in 1990 in Civil Engineering, Łódź University of Technology and his D.Sc.in 2001 in Building Physics, Łódź University of Technology both with honours. His has the position of an ordinary professor at the same University and is also Vice-rector of the University for Innovations and Development. He is also the Head of Building Physics and Building Materials Department. Between 1993 and 1994 he was a Post-doctoral fellow at University of Padova, Italy. In 1999 he joined Oak Ridge National Laboratory, Oak Ridge (TN), USA as a Post-doctoral research associate.
From 2001-2005 he was a visiting professor at the Faculty of Engineering at University of Padua, Italy and again he was a visiting researcher at the same faculty from 2013-2014.
His research areas are :

• Durability of building materials – numerical modelling with mechanics of multiphase porous materials;
• Sustainable buildings, energy efficiency and energy auditing of a building;