Layered double hydroxides (LDH) containing Mg ^II , Fe ^III , and Al ^III in the brucite-like layers and interlayer carbonate (with a constant M ^II /M ^III ratio but varying Al ^III /Fe ^III ratios) have been prepared and characterised by X-ray diffraction, thermal analysis, FT-IR and UV-VIS/diffuse reflectance spectroscopies, temperature-programmed reduction and specific surface area assessment through low temperature adsorption of N ₂ . An Mg,Al-LDH, but with intercalated hexacyanoferrate(III), has been also prepared and characterised, in which simultaneous formation of the carbonate analogue did not occur. Thermal decomposition in air at 450 and 750°C leads to MgO and poorly crystallised MgFe ₂ O ₄ spinel (crystallinity increasing with the iron content), while for the hexacyano-containing sample, crystallization only is observed after calcination at 900°C. This different behaviour has been related to the initial location of the iron ions.

Concrete is a building material commonly used for ages. Therefore, in the result of repairs or demolition of building structures, large amounts of concrete rubble are created, which requires appropriate management. The aim of the realized research was to determine the influence of heat and mechanical treatment of concrete rubble on the properties of recycled aggregate concrete. The research experiment included 12 series, with three variables: X₁—roasting temperature (300, 600, 900 °C), X₂—time of mechanical treatment (5, 10, 15 min), X₃—content of coarse recycled aggregates (20, 40, 60% by volume). Two additional series containing recycled aggregate without treatment and natural aggregate were also prepared. Established properties of individual aggregates have confirmed a positive effect of thermo-mechanical treatment. Then, based on the results of compressive strength, flexural strength, Young’s modulus, volumetric density, water absorption, water permeability and capillarity, the most favourable parameters of heat and mechanical treatment of concrete were determined. The test results showed that appropriate treatment of concrete rubble allows to obtain high-quality coarse aggregate and valuable fine fraction. This was also confirmed by the macro- and microscopic observations of the aggregate and separated cement paste. Works realized on the concrete recycling method resulted in obtaining a patent PAT.229887.