铁尾矿粉的活性及在混凝土中的增强效应

Reactive Activity of Iron Tailings Powder and its Enhancement Effect upon Concrete

进行了掺磨细铁尾矿粉的水泥标准胶砂试验,引入活性指标、强度贡献值、强度贡献率等概念对富硅铁尾矿粉在不同养护条件下的活性及在混凝土中的增强效应进行了表征。结果表明:铁尾矿粉比表面积的增加对铁尾矿活性影响较小,而养护条件对其活性影响显著;铁尾矿粉在标准养护、90℃热水养护及200℃高温养护下基本不具备火山灰活性,对混凝土的增强效应以微集料填充效应为主;蒸压养护条件下具备明显的反应活性,对混凝土的增强效应显著,比表面积为751 m2/kg、掺量为20%的铁尾矿粉3、28、56 d的强度贡献率分别达到23.5%、27.3%、30.9%;铁尾矿粉的比表面积根据构件养护条件的不同以500～750 m2/kg为宜,对水泥的替代量以20%为佳。

Standard cement mortar tests mixed with finely-ground powder of iron tailings are made. The activity of the silicon-rich iron tailings powder under different curing conditions and its enhancement effect in concrete are characterized by introducing the concept of activity indicators ,the strength contribution value and the strength contribution rate etc.. The results show that mechanical grinding can hardly change the activity of powder of iron tailings while curing conditions go to the opposite. Moreover, the powder of iron tailings does not own the pozzolanie activity under standard curing, 90 ℃ hot water curing and 200 ~C high-temperature curing, and its enhancement effect on concrete mainly belongs to micro-aggregate filling effect. Under autoclave curing conditions, powder of iron railings have a obvious reactivity, and greatly inhance the strengthen of the concrete. With the specific surface area of 751 m2/kg, and the mixing amount of 20% , powder of iron tailings own the strength contribution rate of 23.5% ,27.3% ,30.9% at 3 d,28 d,56 d respectively. According to the different curing conditions, the specific surface area is appropriate to be 500 - 750 m2/kg and the amount of substitute of cement will be 20%.