Thermodynamic modeling of cementitious systems using Gibbs Energy Minimization Software (GEMS) for Geochemical Modeling

If you are a newcomer to GEMS and/or to Cemdata18, it is recommended to follow the examples and tutorials of the course on thermodynamic modelling of cement hydration, which took place in 2020 using GEMS 3.7 and introduced the new database version CEMDATA18.

GEMS course – Lecture 01: GEMS course introduction and cement chemistry

Introduction of the GEMS course and cement chemistry. Review of cement production, clinker phases, cement hydration and solution chemistry. Get familiar with the GEMS by creating a new project using the hydration of C3A + CaO + CaSO4 as an example. 

Cement hydration


GEMS course – Lecture 02: Single calculation using hydration of C3A as an example

Short overview thermodynamic modelling using chemical equilibrium of gypsum as an example. Explanation and installation of GEMS. First tutorial calculations of single systems using hydration of C3A as an example, considering the systems with or without introducing CaO, CaCO3 and CaSO4.

GEMS init

Single system C3A


GEMS course – Lecture 03: Basic principle of process calculation

This lecture shows how to model the influence of limestone or fly ash dosage on the phase assemblages of hydrated cement blends using process calculation. 

Process PC


GEMS course – Lecture 04: Database implemented in GEMS

The lecture covers the introduction of thermodynamic database, Cementdata18 for Portland cement and alkali-activated cement systems, and GEMS structure. Exercise on how to calculate the solubility, speciation and saturation indices using GEMS.



GEMS course – Lecture 05: Thermodynamic modelling of cement hydration

Introduction of Parrot and Killoh model to describe the dissolution of cement clinker phases.  Use the obtained hydration degree of clinker phases to predict the phase assemblages and pores solution chemistry during cement hydration.


Hydration modelling


GEMS course – Lecture 06: Interaction with the environment

This lecture demonstrates how to use process calculation of GEMS to model the interaction of hydrated cements with the environments, such as when exposing the hydrated cements to sodium chloride solution, sodium sulfate solution or atmospheric condition with a predefined CO2 concentration.

Interaction with the environment