铁尾矿加气混凝土的制备和性能

Preparation and Properties of Autoclaved Aerated Concrete Using Iron Ore Tailings

以铁尾矿为主要原料制备加气混凝土,研究了铁尾矿的细度和掺量对其性能的影响。结果表明:随着铁尾矿细度的减小料浆的流动性提高,大量气孔的形成使制品的绝干密度降低;但是,细度过小使料浆的流动性降低,在浇注过程中大量气孔的破裂使制品的绝干密度提高。铁尾矿细度减小可提高水化反应速度,生成更多的水化产物,使制品的抗压强度提高。但是,铁尾矿过细使未反应的原料残核过分细小,不能形成良好的气孔结构,导致其抗压强度降低。提高铁尾矿的掺量能使水化产物之间的空隙充分填充,制品的绝干密度随之提高。铁尾矿掺量的提高使托贝莫来石的数量增加,由针片状变为短纤维状,相互交叉形成了网状结构,使制品的抗压强度提高;但是铁尾矿掺量过高使结晶良好的托贝莫来石数量减少,网状结构变得相对松散,导致制品的抗压强度降低。

Iron ore taUings are used as raw materials to prepare autoclaved aerated concrete （AAC）. The effects of fineness and content of iron ore tailings on the properties of AAC were investigated. The results show： as the fineness of iron ore tailings decreases, the mobility of slurry increases, a formation of lot of fine and even bubbles decrease the density of bulks; however, too fine tailings lowers mobility of slurry and a lot of bubbles crack while pouring, which increases density. The decrease of fineness of tailings leads to increase of the hydration reaction rate, generate more hydration products, so compressive strength of bulks increases. But, too fine tailings results in too fine residual of raw material, which is bad to form good pore structure and lowers the strength. High content tailings can fill completely space among hydration products and increase the bulk density, increase of tailings content increases the amount of tobermorite, and changes the shape of tobermorite from needle-like to short-fiber-like, intersection of which forms network structure and increases the strength. However, too high content of tailings makes the connection of products and the network structure loose, the amount of tobermorite decrease, which result in decrease of the compressive strength.