Abstract:

To improve the compressive strength of the prepared fly ash/iron tailings based geopolymer (IGF), the effects of n(Na₂O)/n(Al₂O₃), activator modulus, liquid-solid ratio, solidification temperature and iron tailings content on the compressive strength of IGF were analyzed through single factor and orthogonal experiments. The phase changes of IGF were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (FTIR). The results showed that the compressive strength of IGF increased first and then decreased with the increase of activator modulus, n(Na₂O)/n(Al₂O₃), liquid-solid ratio and iron tailings content, and was positively correlated with the curing temperature. The order of influence was: curing temperature > modulus > liquid-solid ratio > n(Na₂O)/n(Al₂O₃). SEM and XRD results indicated that IGF contained abundant SiO₂ and Al₂O₃. The hydrated calcium silicate (C-A-H gel and C-S-H gel) generated by the combination of the two materials could make the structure more compact, and improve its durability and strength. In addition, adding iron tailings to fly ash based geopolymers could fill the pore structure of IGF, reduce microstructural damage, increase its density, meet the application standards of building materials, and provide possibilities for seeking cement substitutes and improving industry efficiency.

Key words: iron tailings, fly ash, geopolymers, compressive strength, amorphous gel, orthogonal test

摘要：

为提高制备的粉煤灰/铁尾矿基地质聚合物（IGF）抗压强度，通过单因素和正交实验分析了n(Na₂O)/n(Al₂O₃)、激发剂模数、液固比、固化温度、铁尾矿掺量对IGF抗压强度的影响，并结合扫描电子显微镜（SEM）、X射线衍射（XRD）、红外光谱（FTIR）对IGF物相变化进行了表征。结果表明，IGF的抗压强度随激发剂模数、n(Na₂O)/n(Al₂O₃)、液固比和铁尾矿掺量的增加呈先增后减趋势，与固化温度呈正相关，影响顺序为固化温度>模数>液固比>n(Na₂O)/n(Al₂O₃)。SEM和XRD结果显示IGF中含有丰富的SiO₂和Al₂O₃，两者结合生成的水化硅酸钙（C-A-H凝胶和C-S-H凝胶）可使材料结构更加致密，提高其耐久性和强度。此外，在粉煤灰基地质聚合物中添加铁尾矿可以填充IGF的孔隙结构，减少微观结构的破坏，使其致密性增加，从而满足建筑材料的应用标准，并为寻求水泥替代品、提高行业效率提供了可能。

关键词: 铁尾矿, 粉煤灰, 地质聚合物, 抗压强度, 无定形凝胶, 正交实验