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CemGEMS web app tutorial

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

Accessing phaseAliases table

In an existing recipe, the phaseAliases table can be selected by clicking on a triangle near the "phasesAliases" entry, located below the horisontal bar charts. The expanded table looks like this:

Screen image

The table has several columns, but 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 the 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.

Attention!

The template phaseAliases table is automatically included when a new recipe is created. Hence, any changed restrictions for phases will only appear in this recipe and any recipes cloned (duplicated) from it. The changes in the phaseAliases table made in the 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 of GEM-equilibrated 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 the 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. any showing 1 species in the "Nspecies" column). This positive AMR amount must not be too large, otherwise it may violate the mass balance and the GEMS calculation will fail.

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

Based on expert knowledge, the most frequently suppressed phases in hydrated cement systems are already suppressed in the phaseAliases template. Some other phases, such as siliceous hydrogarnets or zeolites may also need to be suppressed or allowed, depending on cement type, blending, temperature and other factors considered in cement chemistry and thermodynamics. For instance, in an iron-rich blended cement, it could make sense to remove restrictions from Aft-AlFe-ss and AFm-AlFe-ss solid solutions and restrict AFm-$-OH-ss and AFt-$-c-ss phases instead.


Last update: January 8, 2021