Effect of thermal pre-treatment conditions of common clays on the performance of clay-based geopolymeric binders
Effect of thermal pre-treatment conditions of common clays on the performance of clay-based geopolymeric binders
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DOI：
10.1016/j.clay.2012.09.010
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发表时间：
2013-03-01
影响因子：
5.6
通讯作者：
Kaps, Ch.
中科院分区：
文献类型：
--
作者：
Seiffarth, T.;Hohmann, M.;Kaps, Ch.
本研究的重点是热预处理条件对常见粘土在碱和碱土溶液中的反应性的影响，在形成地质聚合物粘合剂方面。伊利石和伊利石-蒙皂石粘土分别在氧化和还原气氛中在550和950 ° C之间热活化。材料和结构的变化，其特征在于通过不同的方法，如热分析，XRD和溶解测试。在碱性介质中进行等温量热测量以表征反应过程。通过碱活化的地质聚合物反应的原材料的潜力可以从碱性溶液中可溶性Si/Al的摩尔比导出。采用Chapelle法测定了预处理后样品的火山灰活性，发现随着预处理温度的升高，可溶性Si/Al的摩尔比增大。2：1粘土矿物的存在导致Si/Al比在2和3之间，并且表明通过碱活化进行地质聚合物反应的良好潜力。在热预处理过程中，气氛对这种行为有显著的影响。在还原气氛中预处理的情况下，比在氧化气氛中预处理的情况下，在较低的温度下可以获得最大的火山灰性（反应性）。在相同温度下，在还原气氛中煅烧的粘土比在氧化气氛中煅烧的粘土导致更强烈的铝硅酸盐冷凝。这可能是由于在还原性气氛中预处理后可溶性Si/Al比值较高所致。通过抗弯强度测试，对粘土基地聚合物胶结料的性能进行了研究。(c)2012 Elsevier B. V.保留所有权利。
This study focuses on the influence of the thermal pre-treatment conditions on the reactivity of common clays in alkaline and alkaline earth solutions, in respect to form geopolymeric binders. Illite and illite-smectite clays were thermally activated between 550 and 950 degrees C in oxidizing and reducing atmosphere, respectively. Material and structural changes were characterized by different methods, like thermal analysis, XRD and dissolution tests. Isothermal calorimetric measurements were carried out to characterize the reaction process in alkaline media. The potential of a raw material for the geopolymer reaction by alkaline activation can be derived from the molar ratio of soluble Si/Al in alkaline solutions. Additionally, the standard Chapelle test was executed to determine the pozzolanic reactivity.It could be found that the molar ratio of soluble Si/Al increases with increasing pre-treatment temperature. The presence of 2:1 clay minerals results in a Si/Al ratio between 2 and 3 and indicates a good potential for a geopolymer reaction by alkaline activation. This behavior was remarkably influenced by the atmosphere during the thermal pre-treatment. The maximum pozzolanicity (reactivity) could be obtained at lower temperatures in the case of pre-treatment in reducing atmosphere than in oxidizing atmosphere. Clays calcined in reducing atmosphere result in a more intensive condensation of the aluminosilicates than clays calcined in oxidizing atmosphere at the same temperature. That is possibly caused by the higher ratio of soluble Si/Al after pre-treatment in reducing atmosphere.The performance of the clay-based geopolymer binders was determined by means of bending strength measurements. (c) 2012 Elsevier B.V. All rights reserved.