Thermodynamic data for hydrated solids in Portland cement system (CaO-Al2O3-SiO2-CaSO4-CaCO3-Fe2O3-MgO-H2O)
- New version CEMDATA 14.01 available -
The first version of the cement specific cement database CEMDATA was published in 2007-2009 and based on work carried out at Empa (Lothenbach et al., 2008; Möschner et al. 2008, 2009; Schmidt et al. 2008) and a PhD carried out both at the University of Aberdeen and at Empa (Matschei et al, 2008). CEMDATA contains thermodynamic data (solubility product, Gibbs free energy, enthalpy, entropy, heat capacity and molecular volume) for a number of cement phases. Solubility data have been generally calculated based on a critical review of the available experimental data and on additional experiments to derive missing data or to verify the existing data. In addition, some data were estimated based on structural analogues. Where necessary, additional solubility data were measured in a range of temperatures between 0 and 100 °C. The resulting data base covers hydrates commonly encountered in Portland cement systems in the temperature range 0-100 °C, including C-S-H, hydrogarnet, hydrotalcite, AFm and AFt phases and their solid solutions.
CEMDATA contains thermodynamic data for solids found in Portland cement systems, evaluated as described in various publications (see below). Its applicability to Portland cement systems has been investigated in a number of studies.
CEMDATA at 25 °C
At 25 °C the solubility products (KS0) of the CEMDATA data set is fully consistent with the thermodynamic data for aqueous species, gases, and common minerals such as portlandite or gypsum, provided in the Nagra/PSI-Thermodynamic Data Base (Hummel et al., 2002) and can be used together with the Nagra/PSI TDB in any thermodynamic modelling software.
CEMDATA at 0-100 °C
The CEMDATA07 data base covers hydrates commonly encountered in Portland cement systems in the temperature range 0-100 °C. In the temperature range 0-100 °C the CEMDATA data base is compatible with the GEMS default kernel database (GEMS version of Nagra-PSI 01/01 data base). Hence, the CEMDATA files comprise a specific extension to the GEMS kernel data base. A download in GEM-Selektor (Gibbs Energy Minimization) format is available.
Download of the GEMS version of CEMDATA14
Further information on GEMS see:
Download of CEMDATA07
CEMDATA07 can be downloaded here.
Download of the PHREEQC version of CEMDATA07
CEMDATA07 data base developed at Empa (see CEMDATA07 website for more information) together with the auxiliary information from the Nagra/PSI-Thermodynamic Data Base was converted to PHREEQC-format for temperatures 0-50 °C by Jacques 2009.
Alternative C-S-H model CNASH by Rupert Myers
The sublattice solid solution models for CSH developed by Dmitrii Kulik which is used in the Cemdata14 database is closely related to the structure of C-S-H and tobermorite, and therefore able not only to model the solubility and the chemical composition of the C-S-H, but also to predict the mean silica chain length consistent with the 29Si NMR data. In such models, the C-S-H stoichiometry is represented by building units to describe the C-S-H structure, such as silica dimer, CaO in the main layer, bridging tetrahedra, charge balancing ions, … . A model of this kind seems complicated, but has the advantage that it has the closely related to the C-S-H structure. In addition, such models can easily be extended to account for the uptake of aluminium, calcium, alkalis or other ions by adding them to the respective building units. A recent extension by Rupert Myers allows to model aluminium and alkali uptake in low Ca/Si C-S-H (such as present e.g. in alkali activated slags) using a solid solution approach. The existing C-S-H model can be replaced by the by the CNASH model ( link…); however be aware that this model is valid for low Ca/Si C-S-H only.
Installation of CNASH
The CNASH_ss thermodynamic model is available as an extension to the CEMDATA thermodynamic database. To install the CNASH_ss thermodynamic model in GEM-Selektor v. 3: