Blends of fly ash and natural calcite, mechanically activated for 0–400 s in a planetary mill, were used to synthesize geopolymers at ambient temperature. The calcite content in the blends was 0–10 wt.%. Sodium hydroxide solution was used as an alkaline agent. Mechanical activation of the raw material considerably enhanced its reactivity with respect to the alkaline agent, as was observed using Fourier-transform infrared spectroscopy, isothermal conduction calorimetry, thermogravimetry coupled with mass spectrometry analysis of the evolved gas, and SEM/EDS. The addition of calcite to the fly ash improved the compressive strength of the geopolymers, especially during the early age of curing. For 7 d aged geopolymers based on the 90% fly ash + 10% calcite blend, the strength was 8.0-, 3.5- and 2.9-fold higher than that for the geopolymers based on the unblended fly ash for 30 s, 180 s and 400 s mechanical activation time, respectively. Using Mössbauer spectroscopy, it was revealed that iron present in the fly ash did not play a significant part in the geopolymerization process. The dominant reaction product was sodium containing aluminosilicate hydrogel (N-A-S-H gel). Calcite was found to transform, to a small extent, to vaterite and Ca(OH)₂ in the course of the geopolymerization.

中文翻译：

---

粉煤灰基地质聚合物的合成：方解石添加和机械活化的影响

粉煤灰和天然方解石的混合物在行星式磨机中机械活化了0–400 s，用于在环境温度下合成地质聚合物。共混物中的方解石含量为0-10 wt。％。氢氧化钠溶液用作碱性试剂。如使用傅立叶变换红外光谱，等温传导量热法，热重分析结合放出的气体的质谱分析和SEM / EDS所观察到的那样，原料的机械活化大大增强了其对碱性试剂的反应性。在飞灰中添加方解石可改善地质聚合物的抗压强度，特别是在固化的早期。对于基于90％粉煤灰+ 10％方解石掺合物的7天老化土聚合物，强度为8.0-，3.5-和2。在30 s，180 s和400 s的机械活化时间内，其含量分别比未掺粉煤灰的地聚合物高9倍。使用穆斯堡尔光谱法，发现粉煤灰中的铁在地聚过程中没有发挥重要作用。主要的反应产物是含钠的铝硅酸盐水凝胶（NASH凝胶）。方解石被发现在很小的程度上转变为球v石和Ca（OH）₂在地聚过程中。