JAC Library

The JAC Library is a C++ program library for calculation of ion activities, water activity and saturation ratios of salt mixtures using Pitzer's ion interaction model. Details about the model, its parametrization and implementation can be found in the article:

Steiger M et al., An improved model incorporating Pitzerís equations for calculation, Constr Build Mater (2007), doi:10.1016/j.conbuildmat.2007.04.020

The library was written by Jana Kiekbusch and Andreas Nicolai and is placed under the LGPL (an open-source license that also allows using the library in commercial products). The library is actively maintained and extended by the authors. And, btw, the name JAC stems from "Jana's ACtivity Library".


The Jac library contains an up-to-date parametrization for the system Na-K-Cl-NO3-SO4. Note that due to a typesetting-fault the parametrization printed in the article is partly incorrect. Please use only the parametrization provided in the library.

The parametrization for the Pitzer model was provided by Dr. Michael Steiger of the University Hamburg. If you have questions regarding the parametrization, please contact Dr. Steiger at:


JacTool is a small demonstration program that uses the Jac library and calculates saturation ratios for user definable salt mixtures for various temperatures. In addition to that a complete calculation protocol of all Pitzer equations is generated.

The program is included in the Jac library downloadable package.

Jac Excel Module

The Jac library can also be used directly in Excel for spreadsheet calculations.

The required DLL and Visual Basic macro files are included in the Jac library downloadable package. Also instructions for setting up Excel spreadsheets for use with Jac are provided in the downloadable package.


Library description

The Jac library is written in standard C++ and compiles on Windows and Unix systems. By default it is compiled as static library and linked into user programs. Its usage is really simple and described in its documentation (included in the library download package).

Library download

The archive jaclib.zip [1.1 Mb] contains the source code for the jac library, the internal parametrization, the JacTool demo, the Excel integration Dll and Visual Basic macro file as well as documentation for everything. Simply download the file and uncompress the archive. No installation necessary.

Compilation and usage instructions

For convenient compilation of the library project files are included for Visual Studio 2005 (VC8), Borland C++ Builder 6 and Borland Developer Studio 2007.

Alternatively a build file for the cross-platform build tool CMake is provided (so that the library can be easily compiled under Unix/Linux).

If you have questions regarding compilation and integration of the library into your own codes, please contact the authors: