Application Of Siliceous Iron Tail Mineral Powder As Concrete Admixture

As an industrial waste discharged during the process of iron ore mining,siliceous iron tailing induces very serious pollution to the surroundingenvironment. When the siliceous iron tailing is finely ground to a certain extent,the tailing powder can be produced as a mineralpowder material. In this paper,the feasibility of using ground siliceous iron tailing powder as a mineraladmixture for concrete and its influences on concrete performances werestudied. The purpose of this study is to develop a new type of concrete mineraladmixture and explore a new method of reutilization for siliceous iron tailing.The mineral and chemical composition and grindability of siliceous irontailing were studied in this research. The reactivity index experiment wascarried out on siliceous iron tailing powders with different fineness and also onthe blends of siliceous iron tailing powder with fly ash or ground granulatedblastfurnace slag with different proportions. The concrete strength test was alsoperformed when different water to binder ratios, different additions of siliceousiron tailing powder and fly ash or ground granulated blastfurnace slag wereused. On the other hand, the performances of fresh concrete and the mechanicalproperties, durability and volume stability of hardened concrete were testedwhen different additions of siliceous iron tailing powder were used. Finally,siliceous iron tailing powder concrete has been applied in several actualconstructions. Such conclusions can be drawn as follows:1. The iron tailing used in this study is a typical high-silicon Anshan-typeiron tailing, and it has a worse grindability than cement clinker, similar toblast-furnace slag or steel slag.2. The ground iron tailing powder with a specific area of higher than400m2/kg performs a weak potential hydraulicity, but it doesn’t have an evidentpozzolanic reactivity. The reactivity of siliceous iron tailing powder is lowerthan that of ground granulated blastfurnace slag or fly ash. With the sameaddition proportion, the reactivity of siliceous tailing powder plus groundgranulated blastfurnace slag is higher than that of siliceous tailing powder plus fly ash. The fineness has little significant influence on the activity of siliceousiron tailing powder. The reactivity of siliceous iron tailing powder can bedeveloped better when blended with ground granulated blastfurnace slag thanblended with fly ash.3. Influences of water to binder ratio, addition proportion of mineraladmixtures on compressive strength of concrete incorporating siliceous tailingpowder and ground granulated blastfurnace slag were studied, and it was foundthat more addition of these two mineral admixtures decreases the early agestrength but increases the late age strength of concrete. With the decreasingwater to binder ratio, the effect of mineral admixtures on concrete strength getsmore significant. Therefore, the lower water to binder ratio is more favorable tothe reactivity development of mineral admixtures.4. The addition of binary blend of siliceous iron tailing powder and groundgranulated blastfurnace slag improves workability, mechanical properties anddurability of cocrete, and reduces concrete shrinkage. The fineness of siliceousiron tailing powder has no significant effects on mechanical properties ofconcrete.5. Through strengthening quality management and control of siliceous irontailing selection, grinding, transport, application and other procedures, andadopting suitable mixing proportion parameters, the siliceous iron tailingpowder with a specific area up to a certain value can be applied in actualconstructions as a concrete mineral admixture.