Geochemical thermodynamic equilibrium models have been used for decades to predict the stable assemblage of phases in an aqueous electrolyte. The same kind of calculations have been used to predict phase stability in cement-based materials which, after all, are collections of mineral phases in an alkaline solution. Numerous databases have been compiled with the thermodynamic properties of naturally occurring and synthetic minerals, including aluminosilicates, zeolites, solid oxides, hydrates, sulfates, carbonates, hydroxides, zeolites, and most of the minerals found in cementitious materials.
THAMES (Thermodynamic Hydration And Microstructure Evolution Software) extends this idea to model the 3D microstructure evolution and properties of cement-based materials under a variety of environmental conditions. It combines chemical kinetic models of mineral dissolution, nucleation, and growth with thermodynamic equilibrium calculations (using the GEMS3K library) and a 3D digital image algorithm. It is extensible to a wide range of material systems and phenomena, including hydration of portland cement paste and blended cements—that is, portland cements with partial replacement by pozzolanic components or fillers—leaching of mature binders by groundwater, external sulfate attack, and dissolution-induced creep.
The animation below provides an example of the hydration of a portland cement (Proficiency sample 152 from the Cement and Concrete Reference Laboratory) blended with 20 % of a Class F fly ash. The water-solids mass ratio is 0.45, and the reactions occur at 296 K in a saturated environment for 28 days.
Software
- Please contact us for opportunities to collaborate on developing or using HydratiCA. We are happy to make source code and user guides available for collaborative research.
- More information on GEMS3K library, and links to the software: https://gems.web.psi.ch/
Selected Publications
- JW Bullard, B Lothenbach, PE Stutzman, KA Snyder, Coupling thermodynamics and digital image models to simulate the hydration and microstructure development of portland cement pastes, Journal of Materials Research, 26 (2011) 609-622. DOI: 10.1557/jmr.2010.41
- P Feng, C Miao, JW Bullard, A model of phase stability, microstructure and properties during leaching of portland cement binders, Cement and Concrete Composites, 49 (2014) 9-19. DOI: 10.1016/j.cemconcomp.2014.01.006
- P Feng, EJ Garboczi, C Miao, JW Bullard, Microstructural origins of cement paste degradation by external sulfate attack, Construction and Building Materials, 96 (2015) 391-403. DOI: 10.1016/j.conbuildmat.2015.07.186
- X Li, ZC Grasley, JW Bullard, EJ Garboczi, Computing the time evolution of the apparent viscoelastic/viscoplastic Poisson’s ratio of hydrating cement paste, Cement and Concrete Composites, 56 (2015) 121-133. DOI: 10.1016/j.cemconcomp.2014.11.004
- P Feng, JW Bullard, EJ Garboczi, C Miao, A multiscale microstructure model of cement paste sulfate attack by crystallization pressure, Modeling and Simulation in Materials Science and Engineering, 25 (2017) 065013. DOI: 10.1088/1361-651X/aa758a
- X. Li, ZC Grasley, JW Bullard, P Feng, Creep and relaxation of cement paste caused by stress-induced dissolution of hydrated solid components, Journal of the American Ceramic Society, 101 (2018) 4237-4255. DOI: 10.1111/jace.15587