Alkali activating agents play an important role in dissolving Si and Al atoms to prepare geopolymer precursors from aluminosilicate materials. This study explored the effects of alkali activating agents with different Na2O/SiO2 molar ratios (1.2, 1.3 and 1.5) andL/S (0.65 and 0.87, liquid to solid mass ratio) on the properties and high temperature performance (8001000℃) of metakaolin-based geopolymers containing 15% fly ash substitution and 4% straw fiber. Compressive strength, thermal conductivity, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), thermoanalysis (TG-DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) were used to study the properties and thermal performance of the geopolymers. The results show that when Na2O/SiO2 = 1.2, the compressive strength and thermal conductivity of 7 d are 53 MPa and 0.05276 W?(m·K)-1, respectively. Higher concentration of sodium silicate facilitates the formation of denser microstructure and benefits geopolymerization, which results in a product with higher compressive strength even after thermal treatments.%碱性激发剂在溶解铝硅酸盐材料中的Si和Al原子形成地质聚合物前驱体的过程中扮演重要的角色.文章研究了不同Na2O/SiO2摩尔比(1.2、1.3和1.5)和L/S(0.65和0.87,碱性激发剂与固体原料质量比)组分的碱性激发剂制备含15%粉煤灰取代量、4%秸秆掺量的偏高岭土基地质聚合物的性质及其耐高温性能(8001000℃).抗压强度、导热系数、扫描电镜(SEM)、压汞法(MIP)、热分析(TG-DSC)、X射线衍射(XRD)和傅立叶红外光谱(FTIR)分析用于研究地质聚合物的性质及高温下热行为.研究结果表明,Na2O/SiO2=1.2时,7 d抗压强度有53 MPa,导热系数为0.05276 W?m-1·K-1,且高硅酸钠浓度有利于地质聚合物基体形成更加致密的结构,促进高水平的地质聚合反应,获得更高的抗压强度,即使在高温暴露后仍能保持更好的抗压强度.
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