The project focused on developing innovative and novel formulations for autoclaved aerated concrete (AAC) that could pave the way especially for medium-size manufactures towards the production of low-sulphate AAC. The aim was to reduce significantly the sulphate concentrations in the eluate and, as a consequence, to successfully cope with the exist-ing and coming regulatory restrictions on the recyclability of construction waste from AAC. This should in parallel satisfy European demands for a reduction in the volume of waste and an increased recyclability of building materials. For achieving this goal, the AAC formulations required a cement content as low as possible and an appropriate alternative to the sulphate carriers used to date. The tasks of these two mentioned components (cement, sulphate carrier) should be taken over by calcined clay. Tests results yielded promising results for the complete replacement of the sulphate carrier and a substitution of 20 wt{%} of the cement by either of two types of calcined clay in the AAC formulation. The amount of leachable sulphate ions was reduced by up to 70 {%} compared to the reference samples. The amount of crystalline tobermorite remained constant or was even higher in the samples with calcined clay. The amount of crystalline tobermorite can serve as an indicator of the mechanical strength and shrinkage behavior. However, the mechanical characteristics of autoclaved aerated concrete specimens with calcined clay will be determined in an subsequent project. In this follow-up project, the formulations developed under laboratory conditions are to be implemented on an industrial scale.    «

The project focused on developing innovative and novel formulations for autoclaved aerated concrete (AAC) that could pave the way especially for medium-size manufactures towards the production of low-sulphate AAC. The aim was to reduce significantly the sulphate concentrations in the eluate and, as a consequence, to successfully cope with the exist-ing and coming regulatory restrictions on the recyclability of construction waste from AAC. This should in parallel satisfy European demands for a re...    »