Using PHREEQC to model cement hydration

This paper presents the steps involved in undertaking an analysis of hydrating cements with different levels of limestone powder using the PHREEQC geochemical software with the Notepad++ editor. The analysis begins with determining which solid phases are thermodynamically predicted to precipitate and form using the oxide compositions of commercial CEM I and CEM II/A-L cements. When the phases are known, PHREEQC is programmed to provide predictions of the phase dissolution and phase assemblage over time (here, 1000 days of hydration) as well as the pore solution chemistry. Thermodynamics has been successfully applied to the field of cement hydration to predict phase assemblages and pore solution changes. With an appropriate cement-based thermodynamic database, PHREEQC has the potential to be a very powerful tool in the ongoing development of sustainable cements into the future. The paper also discusses the ongoing work to couple PHREEQC with the HYDCEM model to provide users with an all-in-one platform to undertake a complete simulation of cement hydration.