Background and objectives of the project

Cement clinker production also generates considerable quantities of process dusts, e.g. bypass dusts. The composition of the dusts can also vary within a plant depending on the operating conditions. The relevant constituents include alkali sulphates and chlorides as well as carbonates, free lime and clinker phases. As a secondary constituent, chloride-rich dusts can only be used to a very limited extent for cement production due to the low chloride limit, whereas dusts containing sulphates can be used up to 5 wt.%.

The focus was on investigating the suitability of sulphate-rich process dusts as a secondary constituent for sulphate optimisation. Here, it was examined whether and how early strengths can be improved and the clinker content reduced, particularly in cements with several main constituents. Increased use of sulphate-rich process dusts allows the substitution of natural sulphate carriers (anhydrite, gypsum).

Isothermal heat flow calorimetry records the heat release of the cements over time during the hydration processes. Depending on the main cement constituent, optimal hydration requires different availability of the sulphates. Whether and how these are available is to be understood by tracking the hydration heat release. From the comparison with the usual methods for sulphate optimisation, such as strength and workability tests, it was determined whether isothermal heat flow calorimetry can be used as a fast, simple and cost-effective optimisation method.

The investigations were carried out on the most common types of cement with several main constituents, on cements containing blastfurnace slag and limestone (CEM III/A, CEM II/B-M (S-LL), CEM II/A-LL, CEM II/B-M (Q-LL). Isothermal heat flow calorimeters are already used today by many cement manufacturers to determine the heat of hydration. Therefore, the results can be used directly by SME in the cement industry for a more efficient use of main and secondary cement constituents.


The IGF project 21384 N of VDZ Technology gGmbH, Toulouser Allee 71, 40476 Düsseldorf, Germany, was funded by the Federal Ministry of Economic Affairs and Climate Action via the German Federation of Industrial Research Associations (AiF) within the framework of the programme for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.

This research project has been concluded

Person to contact

Do you have any questions on this subject?

Dr Jörg Rickert
Chemistry and mineralogy

+49-211-45 78-283

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