铁尾矿粉-硅粉矿物掺合料对混凝土性能的影响

Influence of Iron Tailings Powder-silica Fume Mineral Admixture on Concrete Performance

将研磨后的铁尾矿粉末和硅粉分别按照3∶2和4∶1的比例制备了两种复合矿物掺合料替代水泥进行浆体和混凝土试样的制备。通过微观结构分析、强度和耐久性分析对铁尾矿-硅粉复合矿物掺合料浆体和混凝土的基本性能进行了研究,结果表明:随着复合矿物掺合料掺量的增加,试样的水化反应放热量、抗压强度、劈裂抗拉强度和冻融耐久性均逐渐降低;且加入铁尾矿粉可使的硬化浆体试块孔隙结构变大,导致混凝土的抗压强度和冻融耐久性降低;但增加硅粉的掺量可以提高试样的水化反应强度,降低Ca(OH)_(2)的含量,且硅粉水化反应生产的C-S-H凝胶也可以细化孔结构,从而改善混凝土的微观特性、抗压强度、劈裂抗拉强度和冻融耐久性;弥补铁尾矿粉对混凝土性能的负面影响。整体上,改性混凝土的抗压强度在普通混凝土抗压强的85%以上,能满足工程要求。

Two kinds of composite mineral admixtures were prepared by grinding iron tailings powder and silicon powder in the ratios of 3∶2 and 4∶1,respectively to substitute cement for the preparation of mortar and concrete samples.The basic properties of iron tailings-silica fume composite mineral admixture mortar and concrete have been studied through microstructure analysis,strength and durability analysis.The results show that:as the content of the composite mineral admixture increases,the heat of hydration reaction,compressive strength,split tensile strength and freeze-thaw durability of the sample gradually decrease;and adding iron tailings powder can increase the pore structure of the hardened mortar test block,which reduces the compressive strength and freeze-thaw durability of the concrete.However,increasing the amount of silica fume can increase the strength of the hydration reaction of the sample,and increasing the silica fume can reduce the content of Ca(OH)_(2).The CSH gel produced by the hydration reaction of silica fume can also refine the pore structure,thereby Improve the microscopic properties,compressive strength,split tensile strength and freeze-thaw durability of concrete;make up for the negative impact of iron tailings powder on concrete performance.On the whole,the compressive strength of modified concrete is more than 85%of that of ordinary concrete,which can meet engineering requirements.