Preparing autoclaved aerated concrete using high-silicon iron tailing

This study aims to prepare autoclaved aerated concrete (HIT-AAC) using high-silicon iron tailing (HIT) as a single siliceous material. The influence of HIT fineness and mix proportion parameters, including the molar calcium to silicon ratio (Ca/Si), the mass ratio of water to solid materials (W/S), and aluminum powder paste dosage, on the properties of HIT-AAC were investigated. The test indices included slurry fluidity, foaming curve of the HIT-AAC mixture, dry density, and mechanical strength of the HIT-AAC block. Furthermore, the hydration products and microstructure of the HIT-AAC sample were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM). The tested results showed that coarse HIT has adverse effects on the expansion of the HIT-AAC mixture and could not be used for HIT-AAC production. The mechanical strength reached a maximum under the following conditions: HIT-58.3 %, cement-25.8 %, lime-12.9 %, gypsum-3 %, aluminum powder-0.07 %, and W/S-0.5. Microscopic investigation verified the main minerals in HIT-AAC are quartz, tobermorite, hematite, calcite and anhydrite.