In this investigation, the effect of sodium hexafluorosilicate addition on the mechanical and microstructural properties of metakaolin-based geopolymers cured at ambient temperature was evaluated. The geopolymers were manufactured using metakaolin as a raw material with Sodium hexafluorosilicate Na₂SiF₆ powder as an additive, and a mixture composed of NaOH, KOH, and sodium silicate together as an activating solution. The amount of Na₂SiF₆ ranged from 1 to 5%, a (SiO₂ / (Na₂O + K₂O)) modulus of 1.3 and a Si/Al ratio varied between 1.60 and 1.70. Geopolymer specimens cured at room temperature under air for 28 days were characterized, using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (ATG-DTG), scanning electron microscopy (SEM), and compressive tests to assess the microstructure-compressive strength dependency. The findings indicate that the addition of 2% Na₂SiF₆ improves the compressive strength by 28%, but beyond this value, the resistance progressively decreases, this observation was explained by the fact that this additive rises the Si/Al ratio, which led to an increase in the amount of strong Si-O-Si bonds. The reduced RC has been related to the excess amount of Na in the blend that promotes the formation of efflorescence, leading to crack formation, which negatively affects the mechanical properties.

在这项研究中，评估了添加六氟硅酸钠对在环境温度下固化的偏高岭土基地质聚合物的机械和微观结构性能的影响。以偏高岭土为原料，以六氟硅酸钠Na ₂ SiF ₆粉末为添加剂，以及由NaOH，KOH和硅酸钠组成的混合物作为活化溶液，来制造地聚合物。Na ₂ SiF _6的含量为1％至5％，a（SiO ₂ /（Na ₂ O + K ₂O））的模量为1.3，Si / Al比在1.60和1.70之间变化。使用X射线衍射（XRD），傅里叶变换红外光谱（FTIR），热分析（ATG-DTG），扫描电子显微镜（SEM）和压缩试验对室温下在空气中固化28天的地聚合物标本进行表征评估微结构的抗压强度依赖性。研究结果表明，添加了2％Na ₂ SiF ₆将抗压强度提高了28％，但超过此值，电阻逐渐降低，此观察结果是由于该添加剂提高了Si / Al比例，从而导致了较强的Si-O-Si含量增加债券。降低的RC与共混物中过量的Na有关，后者促进了风化的形成，导致裂纹的形成，对机械性能产生负面影响。