Abstract
For comprehensive utilization of solid wastes, the autoclaved aerated concrete (ACC) were prepared by using lead-zinc tailings (LZT) as mainly siliceous materials. The effects of fineness and dosage of LZT on the AAC properties, hydration products and microstructures of AAC were analyzed by the mechanical test, X-ray diffraction analysis (XRD) and scanning electron microscope (SEM). The results show that the ACC containing 62 % LZT (in mass percentage) with a surface area of 325 m2 kg-1 (grinding time of 25 min) can achieve a bulk density of 587 kg m-3 and compressive strength of 4.94 MPa, which is in line with the requirement of A3.5, B06-class AAC products regulated by autoclaved aerated concrete building blocks (GB/T 11969-2008). The mobility of slurry and hydration activity increase with decreasing fineness of LZT. However, the small size of LZT powder and high thickness of the slurry are bad to form good pore structure, which would influence the properties of AAC. When the blending percentage of LTZ is too high, the unreacted LTZ particles increase and accumulate within the system, which reduces the space among them and thus influences the growth and crystallization of hydration products. The main hydration products in the AAC are C-S-H gels and tobermorite- 11 Å.
