Using the Pitzer Model to Predict Aqueous Solution Compositions of Portland Cements Blended with Supplementary Cementitious Materials

Author(s): Dale P. Prentice, Susan A. Bernal, Mark Bankhead, Martin Hayes and John L. Provis
Paper category: Proceedings
Book title: Proceedings of International Conferences (ICACMS) Advances in Construction Materials and systems Vol 2
Editor(s): Manu Santhanam, Ravindra Gettu, Radhakrishna G. Pillai, Sunitha K. Nayar
ISBN: 978-2-35158-194-0
e-ISBN: 978-2-35158-191-9
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 638-647
Total Pages: 10
Language : English

Abstract: Thermodynamic modelling can be used to predict how changes in cement chemistry will affect the nature of the hydration products and corresponding aqueous pore solutions. Current geochemical thermodynamic models primarily use the Debye-Hückel or Davies equations as the basis for determining activity coefficients of aqueous species. Using these equations, good results in predicting the aqueous phase compositions within pure cement systems are obtained; however, for blended cements these simplified equations may provide inaccurate results as pore solution chemistry can become more complex. Using the Pitzer model to determine activity coefficients in blended cement systems can improve the accuracy of simulated aqueous compositions, as long as a suitable parameter database can be made available and validated. The Pitzer model has fitted parameters which describe binary and ternary ion interactions to provide ion-specific activity coefficients for use at high ionic strength, as opposed to the non-specific values provided by the Debye-Hückel or Davies equations. The availability of accurate predicted aqueous solution compositions enables the simulation of phase assemblage of the hydrated blended cements, and the prediction of the main binding phase compositions is improved due to the more accurate simulation of interactions of aqueous ions.

Online publication : 2017
Publication type : full_text
Public price (Euros) : 0.00