Alkali activation of fly ash:: Effect of the SiO2/Na2O ratio Part I:: FTIR study
Alkali activation of fly ash:: Effect of the SiO2/Na2O ratio Part I:: FTIR study
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DOI：
10.1016/j.micromeso.2007.02.055
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发表时间：
2007-11-01
影响因子：
5.2
通讯作者：
Palomo, A.
中科院分区：
文献类型：
--
作者：
Criado, M.;Fernandez-Jimenez, A.;Palomo, A.
本文用红外光谱法研究了碱激发粉煤灰体系的主要反应产物。试验的主要变量为：碱性活化液中可溶性SiO2含量（0%SiO_2、1.62%SiO_2、5.40%SiO_2和9.07%SiO_2）和热固化时间（8h、60和180 d）。所获得的结果表明，在所有情况下形成的主要反应产物是被认为是沸石前体的碱性硅铝酸盐型凝胶。通过红外光谱，它已被证明，有一个不对称的伸缩带（T-O），与铝硅酸盐型凝胶，这可以解释为该凝胶显示两种不同类型的Si-O键：桥和终端键。可溶性二氧化硅的存在改变了反应动力学，并促使形成具有更高百分比的桥键的更多富含Si的凝胶。可溶性二氧化硅的存在也影响结晶速率和形成的沸石的类型（Na-菱沸石、沸石Y、沸石P）。最后，当热固化时间增加时，凝胶经历聚合并且其结构变得高度有序（桥比末端键占优势）（c）2007 Elsevier Inc. All rights reserved.
In this paper the main reaction products formed in alkali activated fly ash systems have been studied by using Infrared Spectroscopy. The main variables of work were: soluble silica content in the alkaline activating solution (0% SiO2; 1.62% SiO2; 5.40% SiO2 and 9.07% SiO2) and thermal curing time (8 h, 60 and 180 days). The results obtained have shown that the main reaction product formed in all cases was an alkaline aluminosilicate-type gel regarded to be a zeolite precursor. By means of the Infrared Spectroscopy it has been shown that there is an asymmetric stretching band (T-O), associated with that aluminosilicate-type gel, which can be interpreted in terms of that gel showing two different types of Si-O bonds: bridge and terminal bonds. The presence of soluble silica modifies reaction kinetics and prompts the formation of more Si-rich gels with a higher percentage of bridge bonds. The presence of soluble silica also affects the rate of crystallization and the type of zeolites formed (Na-Chabacite, zeolite Y, zeolite P). Finally when the thermal curing time increases, the gel undergoes polymerization and its structure becomes highly ordered (with a predominance of bridge over terminal bonds) (c) 2007 Elsevier Inc. All rights reserved.