Research projects

Calcined clays as the main cement constituent are an essential part of the cement industry's decarbonisation strategy. Many clay deposits have iron-rich impurities that form hematite during calcination, which colors the product, the cement and ultimately the concrete red. A reducing atmosphere during calcination and/or cooling can prevent the formation of hematite. Systematic findings on the influence of secondary constituents in clays on their reactivity, emissions and cement-technical properties have hardly been available to date and are to be systematically investigated in the project.

The project systematically investigates the performance and hydration behaviour of ternary cement (KQL) with clinker (K), calcined clay (Q) and limestone (L) as well as key durability aspects of concretes produced with these materials.

In the ZIM research project, used concrete is processed in such a way as to improve the usability of all fractions generated, in particular the crushed sand and the fine fraction. To this end, tests are also being carried out on the pozzolanic reactivation of the recycled concrete fines.

The current requirements for low alkali cements mean that calcined clays can hardly be used as main constituent in such cements due to their alkali content. However, it is known that pozzolanic SCMs contribute to the prevention of ASR. The aim of the research project is therefore to systematically investigate the contribution of calcined clays to the prevention of ASR.

In the IGF research project 23643 N, relationships between the particle size distribution of different cement compounds (clinker, calcined clays and limestone powder), and their reactivity and influences on cement performance are being systematically investigated.

In the research project, testing methods were put to the test and an evaluation concept for fresh concrete leaching was developed. The derived maximum permissible releases were significantly lower than in all applications, so that, from the research centres' point of view, there is no need for testing or regulation of fresh concrete releases.

The possibilities and limits of using recycling (RC) gypsum for cement production were determined. The findings of the research project will help to compensate for the future elimination of gypsum from flue gas desulphurisation (FGD), conserve natural resources and reduce the amount of waste going to landfill

The research project analysed whether sulphate-rich process dusts can be used to optimise the sulphate content of cements, thereby saving anhydrite/gypsum and, in particular, improving the early strength of cements with several main constituents. Furthermore, it was to be determined whether isothermal heat flow calorimetry can be used as a fast and cost-effective investigation method for this purpose.