Research projects

The future of concrete recycling is taking shape here: through the targeted sequestration of CO₂ in demolition concrete, the project is investigating an innovative approach to improving the separation of aggregate and cement stone during demolition. The optimized separation of aggregate and hardened cement paste enables the recovery of valuable secondary materials and, thus, makes an important contribution to strengthening the circular economy in the construction sector in order to achieve sustainability goals.

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.

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 this research project, IR spectroscopy in combination with mathematical tools (chemometrics) is going to be evaluated as an analytical method for the characterisation of silica based materials, primarily X-ray amorphous materials, with regard to the reliable determination of the composition of material mixtures with X-ray amorphous materials (e.g. ternary cements with calcined clay and/or recycled concrete fines). In a next step, the findings on the analytical method and evaluation routines developed for cement are going to be evaluated with regard to their transferability to siliceous aggregates for estimating its alkali sensitivity.

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.

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.

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.

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.