不同细度铁尾矿粉对水泥基材料性能的影响

Influence of iron tailing powder of different fineness on properties of cement-based material

本文研究了掺入四种平均粒径分别为110μm、90μm、45μm、25μm的铁尾矿粉(ITP1、ITP2、ITP3、ITP4)的水泥基材料的力学性能、微观结构和水化产物.研究结果表明,当铁尾矿粉以5%的质量百分比替代水泥时,掺加ITP1、ITP2、ITP3、ITP4的砂浆28 d抗压强度与纯水泥砂浆相比分别提高了11%,3%,13%和29%.当铁尾矿粉替代水泥的质量百分比大于5%时,随着铁尾矿粉掺量的增加,掺四种不同细度铁尾矿粉的砂浆强度都会逐渐降低.为了保证铁尾矿粉砂浆的强度不低于纯水泥砂浆强度,ITP1、ITP2、ITP3、ITP4替代水泥的质量百分比分别不应超过10%、5%、10%和20%.此外,通过背散射扫描电镜观察到,铁尾矿粉在28 d龄期时虽未发生明显水化,但较细的铁尾矿粉末与水泥临界区生成了少量胶凝成分C-S-H,说明机械研磨对铁尾粉火山灰活性有少许激发作用.扫描电镜结果显示,铁尾矿粉的细度越细,其填充效果越好,掺少量铁尾矿粉的水泥基材料力学性能的提高主要归因于铁尾矿粉的填充效果.

In this paper,the mechanical properties,microstructures and hydration products of cement-based materials containing four kinds of iron tailings powder(ITP1,ITP2,ITP3,ITP4)with average diameters of 110μm,90μm,45μm,25μm were studied.Results show that the 28-day compressive strength of mortars with ITP1,ITP2,ITP3 and ITP4 were 11%,3%,13%and 29%is higher than that of pure cement mortar respectively when the cement was replaced by 5%iron tailing powder in mass.Meanwhile,the addition of iron tailing powder more than 5%would turn to decrease the mechanical properties gradually,regardless of the sizes of iron tailing powder.In order to ensure that the strength of mortars containing ITP1,ITP2,ITP3 and ITP4 were not lower than that of pure cement mortar,the respective maximum replacement levels of ITP1,ITP2,ITP3 and ITP4 were 10%、5%、10%and 20%respectively.In addition,a small amount of cementitious C-S-H was formed in the critical zone between fine iron tailings powder and cement,which indicated that mechanical grinding has a little stimulating effect on the pozzolanic activity of iron tailings.The improving of the mechanical properties of cement-based material containing small amount iron tailing powder could be attributed to the filling effect,because the better filling effect could be observed by SEM in the mortar containing finer the iron tailing powder.