Possibilities of Aerated Concrete Recyclate and Fluid Fly Ash Usage in Autoclaved Composite Production

Waste aerated concrete grit is produced either directly in the aerated concrete plant or subsequently on the building site. The options for handling aerated concrete grit are two. Either it can be used as a construction material, e.g. in the form of light aggregate or as a raw material for the production of aerated concrete. The subject of this article is the verification of aerated concrete grit as a raw material suitable as an additive in the technology for the production of aerated concrete. The actual solution consisted of the creation of laboratory-autoclaved composites without a porous structure to eliminate the accompanying effects of the technology. The grit was tested in different silica sand substitution ratios (10%, 20%, 30%, 40%) in the reference mixture, based on real production technology. On the basis of physico-mechanical properties and microstructural analysis (XRD, SEM), porous concrete was found to be suitable as a raw material even with 40% sand substitution, where the properties of reference aerated concrete were retained. At doses of 10 and 20%, even the performance benefits of the composite have increased.