This study investigated the effect of elevated temperatures on the residual mechanical behaviors of geopolymer mortars with initial damage induced by mechanical load. Geopolymer mortar was prepared using different fly ash/ ground granulated blast furnace slag (GGBFS) ratios and was activated by sodium silicate and sodium hydroxide solution. The physical properties and residual mechanical strength were investigated and compared with those of Portland cement mortar (PCM). After elevated temperature exposure, microstructure of GSM was studied by various microcharacterizations. The results show that before the exposure to high temperature, the addition of GGBFS increased the compressive strength of GSM, but made it more sensitive to the preloading damage, leading to the increased strength loss. After exposed to combined preloading damage and high temperature exposure, the GSM exhibited lower residual strength than the ones only suffered from preloading damage or high temperature exposure. Compared to the PCM, GSM with GGBFS performed better at temperature of 300 °C, but became worse at temperatures of 500 and 700 °C due to severe damage caused by combined high load level and large heat exposure. Finally, a low percentage of GGBFS (less than 20%) can be considered as an optimal amount for the GSM to achieve excellent fire resistance capacity.

中文翻译：

---

粉煤灰/GGBFS基地质聚合物砂浆的耐高温负荷诱导损伤

本研究调查了高温对由机械载荷引起的初始损伤的地质聚合物砂浆残余力学行为的影响。使用不同的粉煤灰/磨碎的高炉矿渣 (GGBFS) 比率制备地质聚合物砂浆，并通过硅酸钠和氢氧化钠溶液进行活化。研究了物理性能和残余机械强度，并与硅酸盐水泥砂浆（PCM）进行了比较。在高温暴露后，通过各种微观表征研究了 GSM 的微观结构。结果表明，在暴露于高温之前，GGBFS的加入提高了GSM的抗压强度，但使其对预压损伤更加敏感，导致强度损失增加。在暴露于预压损伤和高温暴露组合后，GSM 的残余强度低于仅遭受预压损伤或高温暴露的残余强度。与 PCM 相比，具有 GGBFS 的 GSM 在 300 °C 的温度下表现更好，但由于高负载水平和大量热暴露造成的严重损坏，在 500 和 700 °C 的温度下表现更差。最后，低百分比的 GGBFS（小于 20%）可以被认为是 GSM 实现优异耐火能力的最佳量。但在 500 和 700 °C 的温度下，由于高负载水平和大量热暴露造成的严重损坏，情况变得更糟。最后，低百分比的 GGBFS（小于 20%）可以被认为是 GSM 实现优异耐火能力的最佳量。但在 500 和 700 °C 的温度下，由于高负载水平和大量热暴露造成的严重损坏，情况变得更糟。最后，低百分比的 GGBFS（小于 20%）可以被认为是 GSM 实现优异耐火能力的最佳量。