Geopolymers have the potential to function as an environmentally friendly substitute for ordinary Portland cement, with up to 80% less CO2 emission during production. The effect is best utilized for geopolymers prepared with amorphous silica instead of waterglass (Na2xSiyO2y+x) to adjust the Si:Al ratio. The reactivity of the precursors with the alkaline activator affects the final mineralogical properties of the binder. The purpose of the present study was to investigate the amount of different phases formed during geopolymerization and to understand the quantitative evolution of carbonation during geopolymer synthesis by determining the solubility of metakaolinite and amorphous SiO2 in NaOH at various concentrations. The solubility was studied by ICP-OES measurements. X-ray diffraction was used for qualitative and quantitative phase analysis of the geopolymers. The solubility of the precursors increased with calcination temperature of metakaolinite, reaction time for amorphous SiO2, and at higher NaOH concentrations. Partial dissolution resulted in free Na+, which is a source for the formation of carbonates in the geopolymers. Thermonatrite occurred prior to trona formation in all samples.

中文翻译：

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前体的溶解度和无水玻璃地聚合物的碳化

地质聚合物有潜力作为普通波特兰水泥的环保替代品，在生产过程中减少多达 80% 的二氧化碳排放。该效果最适合用无定形二氧化硅而不是水玻璃 (Na2xSiyO2y+x) 制备的地质聚合物来调整 Si:Al 比率。前体与碱性活化剂的反应性影响粘合剂的最终矿物学性质。本研究的目的是通过测定不同浓度的偏高岭石和无定形 SiO2 在 NaOH 中的溶解度，研究地质聚合过程中形成的不同相的数量，并了解地质聚合物合成过程中碳酸化的定量演变。通过ICP-OES测量研究溶解度。X 射线衍射用于地质聚合物的定性和定量相分析。前驱体的溶解度随着偏高岭石的煅烧温度、无定形 SiO2 的反应时间和较高的 NaOH 浓度而增加。部分溶解导致游离 Na+，这是在地质聚合物中形成碳酸盐的来源。Thermonatrite 发生在所有样品中天然碱形成之前。