Thermodynamic data

Cemdata
 

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.
In order to model other systems, e.g. blended or alternative cements, cement degradation, or sorption of metals in cement matrix, the CEMDATA must be critically evaluated and extended with additional pure solids and/or solid solutions.

 

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

To use the CEMDATA14 data base in GEMS-PSI package, please download it to your hard disk and perform the following steps:

  1. Unzip the downloaded zip file (contains a directory named "DB.default") into a temporary directory, e.g. as /Tempfiles/DB.default
  2. Find where you have GEMS installed (on Windows, usually under C:\GEM335) the C:\GEMS335/GEMS3-app/Resources/DB.default directory. Remove in that directory all files that contain "specific" as part of the file name (if any such files are present there).  Under Linux, this may need a root password.
  3. Copy all files from /Tempfiles/DB.default into the C:\GEMS335/GEMS3-app/Resources /DB.default directory.
  4. Start GEMS and create a new project. In the "Selection of databases..." dialog, select  "psi-nagra" and "3rdparty : cemdata ".  This will link the Cemdata database files as a specific extension to the general PSI/Nagra database.
  5. Select Independent Components to form the system and click "Ok" to proceed as usual.

 

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.

Please use this link to access the webpage of the Belgian Nuclear Research Center to download the PHREEQC version of CEMDATA07 or use the alternative download here.

 

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:

  1. For GEMS 3.2:
    Download and unzip the supplementary information files “mmc1.zip”, “mmc2.zip” and “mmc3.zip” from dx.doi.org/10.1016/j.cemconres.2014.07.005 or “CNASH_32.zip” from this webpage.
  2. For GEMS 3.3:
    Download and unzip the supplementary information files “mmc1.zip”, “mmc2.zip” and “mmc3.zip” from “CNASH_33.zip” from this webpage
  3. This will produce three .txt files: “CNASH_txt” contains information about the phase definition, i.e. end-member activity coefficient relationships; “DComp end members.txt” contains thermodynamic data for the ‘dependent component’ end-members (T2C*, T5C* and TobH*); and “ReacDC end members.txt” contains thermodynamic data for the ‘reaction-defined dependent component’ end-members (5CA, INFCA, 5CNA, INFCNA, INFCN).
  4. Open an existing modelling project or create a new modelling project in GEM-Selektor v. 3.
  5. Go into ‘Database Management Mode’.
  6. Install the ‘dependent component’ end-members by clicking on the ‘DComp’ button then click the drop down list ‘Record List’ and select ‘Restore…’. Open the file ‘DComp end members.txt’. These end-members should now be present in the list of dependent components.
  7. Click on the ‘ReacDC’ button then select ‘Record List’ > ‘Restore…’ and open the file ‘ReacDC end members.txt’. The ‘reaction-defined dependent component’ end-members should now be present in the list of ReacDC components. 
  8. Click on the ‘Phase’ button, then select ‘Record List’ > ‘Restore…’ and open the file ‘CNASH_ss.txt’ to install the phase definition for the CNASH_ss thermodynamic model. CNASH_ss should now be present in the list of phases.
  9. Enter ‘Equilibria Calculation Mode’ and open the same project that was previously selected. A pop-up window will appear, asking for permission to insert the installed end-member or CNASH_ss phase definitions into the project database. Click the ‘Do it for All’ button. The CNASH_ss thermodynamic should now be installed in this project.

References