Preparation of autoclaved aerated concrete using copper tailings and blast furnace slag

Based on the background that large amount of copper tailings are stockpiled in China, the utilization of skarn-type copper tailings to prepare autoclaved aerated concrete (AAC) was studied. The AAC samples were prepared on a laboratory scale with a dry density of 610.2 kg m⁻³ and compressive strength of 4.0 MPa. Compared with the traditional AAC, lime was totally substituted by skarn-type copper tailings and blast furnace slag in order to develop a potential technique of reducing CO₂ emission during the AAC production process. The samples of different curing stage were examined by XRD, FESEM as well as ²⁹Si and ²⁷Al NMR analyses. Results show that the main minerals in the AAC product are tobermorite-11 Å, anhydrite, augite, quartz, calcite and dolomite, with small amount of other minerals brought in by the copper tailings. It was also suggested that most minerals in the copper tailings participated in the hydration reaction during the procuring process, and the chemical elements in them got into the structure of platy tobermorite in the subsequent autoclaving process.