铁尾矿砂水泥砂浆抗压强度及微观结构分析

Analysis of Compressive Strength and Microstructure of Iron Tailings Sand Cement Mortar

为研究铁尾矿砂掺入量对水泥砂浆抗压强度及微观结构的影响,采用高硅型铁尾矿废石破碎而来的铁尾矿砂,以不同质量铁尾矿砂等比例代替天然河砂配制水泥砂浆进行抗压试验。对比铁尾矿砂与天然河砂在组成成分、粒形、粒径、级配分布上的差异,分析铁尾矿砂与天然河砂比例不同时水泥砂浆立方体试件的破坏形态以及抗压强度。并使用扫描电子显微镜(SEM)着重分析完全替代下铁尾矿水泥砂浆与天然河砂水泥砂浆的细骨料与水泥胶体的交界面形态及水化产物微观形貌。结果表明:所用铁尾矿砂SiO2含量较高,属于高硅型铁尾矿,由于机制原因造成其多棱角且表面粗糙。替代率对铁尾矿水泥砂浆立方体试件破坏形态没有显著影响,不同替代率下铁尾矿水泥砂浆力学性能均优于天然河砂水泥砂浆。铁尾矿砂的加入会导致水泥砂浆内部结构劣化,但由于铁尾矿砂多棱角、表面粗糙与水泥胶体的机械咬合力较大,而且高硅型铁尾矿砂自身强度较高,弥补了由于结构劣化造成的力学性能损失,使铁尾矿水泥砂浆的基本力学性能仍能满足要求。

In order to study the influence of the content of iron tailings on the compressive strength and the microstructure of cement mortar under replacement of iron tailings,iron tailings sand obtained by crushing high-silicon iron tailings waste rocks was used to prepare mixed cement mortar with different quality iron tailings sand instead of natural river sand in equal proportion for compressive test.Comparing the differences in composition,grain shape,particle size and gradation distribution between iron tailings sand and natural river sand,the failure modes and compressive strength of cubic specimens of mixed cement mortar were analyzed.Scanning electron microscope(SEM)was used to analyze the interface morphology of fine aggregate and cement colloid and the micro-morphology of hydration products under the complete replacement of iron tailings cement mortar and natural river sand cement mortar.The results showed that the silicon dioxide content of iron tailings used is high,which belongs to Anshan high-silicon iron tailings,and it has many edges and rough surfaces due to mechanism reasons.The replacement ratio has no significant effect on the failure mode of cubic specimens of iron tailings cement mortar,and the mechanical properties of iron tailings cement mortar are better than those of natural river sand cement mortar under different replacement ratios.The addition of iron tailings will lead to the deterioration of the internal structure of cement mortar.However,due to the angular and rough surface of iron tailings,the mechanical bite force between iron tailings and cement colloid is large,and the high strength of iron tailings itself makes up for the loss of mechanical properties caused by structural deterioration,so that the basic mechanical requirements of iron tailings cement mortar can still be met.