Thermodynamics and Volume Stability of Hydrate Phases with Sulfate Content

Date This project started on 15 September 2006 and ended on 14 September 2009

Status This project is Finished

Authors
Ecole Polytechnique Fédérale de Lausanne, Switzerland 
Lafarge Centre de Recherche, France 
OXAND S.A., France 
University of Aberdeen, UK
Objectives
State of the Art : Portland cement formulation is a compromise. Both short and long term properties need to be controlled. Calcium sulfate is added to extend workability times of fresh cement, but concerns persist about the long-term impacts on performance, particularly when the environment contributes sulfates.
Objectives and innovation : We return to fundamentals, based on physics and chemistry, to develop a quantitative scheme to calculate mineral balances and hence changes in the specific volume of solids. Sensitivity studies will be made to enable problem compositions to be avoided. The model will be generic, thus obviating need for a massive programme of research and will provide a flexible tool for engineers. Collaboration with industrials will help the transfer of basis knowledge and required data to support model developed in Project 9 (Oxand), and provide the means to carry out the verification of new data developed against existing knowledge base pertaining to sulfate attack and related volume stability, durability and strength issues (Lafarge).

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