Cement grouts are used for a wide range of applications in the construction industry. These grouts require a high workability and superplasticising admixtures. It has been found that some cement pastes and mortars perform better (ie flow faster and are workable for longer times without bleed and segregation) in some countries than in others. These problems may be solved on an empirical basis, but in this project the mechanisms involved are investigated in order to predict the performance of the cement pastes more effectively. To do this, a relationship between the rheological properties of the cement paste and the chemical components, especially the different kinds of sulphates, of the Portland cement is established. First a relationship between the simple industrial tests, such as the mini slump flow cone and the efflux flow cone, and the rheological properties obtained by a rheometer has to be established. Subsequently, as set of cements with different sulphates in them were tested in the rheometer. The results show that the use of gypsum gives substantially superior performance compared to anhydrite.
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