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CemGEMS web app tutorial

Working with table of name aliases and amount restrictions for equilibrium phases

Accessing phaseAliases table

This table is only accessible in the "Expert" view that can be selected in the upper right corner of web app page, next to "View". Select an existing recipe, and clicking on a triangle near the "phasesAliases" entry, located below the horisontal bar charts. The expanded table looks like this:

Screen image

The phasesAliases table has several columns, only three with white background are editable.

Editing aliases of names of GEMS phases

In the "Phase alias (recipe)" column, you can change the alias of any phase name from GEMS database, for instance "AqueousSolution" for "aq_gen". The aliases will appear in place of GEMS phase names in:

  • Phases column of the Equilibrated part of the outputResults table;
  • equilibrateChart legend for Results stacked bar;
  • plot frame legend and data table for Volumes, Masses and other properties of phases.


The template phaseAliases table is automatically included when a new recipe is created. Hence, any changed alias will only appear in this recipe and any recipes cloned (duplicated) from it. The changes in the phaseAliases table made in current recipe will be saved when it is equilibrated or cloned, and will affect all its child processes and plots. If there are several recipes in one recipe document, the same phaseAlias table (edited or not) applies to all recipes.

Changing restrictions on amounts GEMS phases

Other editable columns in the phaseAliases table are "Restricted?" and "To amount". The former contains checkboxes, most of which are empty (false). Activating such checkbox for a phase will cause the GEM solver to apply AMR (additional metastability restriction) fixing the amount of this phase in equilibrium state to a respective metastable value set in the "To amount" column (0 by default).

AMR = 0 means that the phase (an all its components) will be constrained to zero amounts and therefore will not appear in the equilibrated assemblage. Non-zero value can be set for any pure phase (i.e. the one showing 1 species in the "Nspecies" column). Take care that this positive AMR amount is not too high, otherwise it may violate the mass balance and the GEMS calculation will fail.

To activate the previously suppressed phase, just uncheck the respective checkbox.

In practice, most frequently suppressed phases in hydrated cement systems are Al hydroxides, kaolinite, thaumasite, hematite, magnetite, and some clinker phases (belite, ...). Siliceous hydrogarnets or zeolites may also need to be suppressed depending on cement type, blending, temperature and other factors considered by experts in cement chemistry and thermodynamics.

Last update: June 9, 2020