Background and aims of the project
When alkali-reactive aggregates are used in concrete, the use of low alkali cements can be an appropriate measure to prevent deleterious alkali-silica reaction (ASR). This also applies to many recycled aggregates, the use of which is increasing due to the growing importance of the circular economy in the construction sector. Due to the decarbonisation of the cement and steel industry, however, the availability of the types of cement currently used as low alkali cements is expected to decrease.
The requirements for low alkali cements mean that the corresponding use of innovative cements with calcined clays is hardly possible in practice. However, it is known that these materials contribute to the prevention of ASR. The aim of the research project is therefore to systematically investigate the contribution of calcined clays to ASR prevention. To this end, the effects of various factors (especially chemistry and mineralogy of the raw clay, calcination temperature) on the effective alkali content of cements with calcined clays will be analysed. The results will be verified with concrete prism tests. Finally, tests are to show whether the special methods for the verification of low alkali properties for cements containing slag sand and/or limestone can also be used for cements with calcined clays. This would enable the adaptation of the regulations and thus the production of low alkali cements with calcined clays.
