Size distribution of unburned carbon in coal fly ash and its implications
Size distribution of unburned carbon in coal fly ash and its implications
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DOI：
10.1016/s0016-2361(03)00255-2
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发表时间：
2004-01-01
期刊：
影响因子：
7.4
通讯作者：
Suuberg, EM
中科院分区：
文献类型：
--
作者：
Külaots, I;Hurt, RH;Suuberg, EM
一组九个粉煤灰，从美国的各种公用事业，分级标准干筛技术。测量了不同粒度级分的碳含量，并用显微镜检查了碳颗粒的性质。F类灰和C类灰中碳的分布存在显著差异。“泡沫指数”测试通常用于快速评估混凝土用火山灰添加剂的加气适用性。该试验测量粉煤灰中碳对引气外加剂（AEAs）的吸附。本试验应用于不同的灰馏分证实，最小粒径的灰馏分作出主要贡献的AEA吸附。当基于表面积进行比较时，来自F类灰分的碳具有与来自C类灰分的碳相当的AEA吸附能力。使C类碳明显“更糟糕”的是它们具有比F类碳高得多的表面积的事实（并且仅凭借大多数C类灰烬中的低碳质量，这些灰烬的问题并不常见）。从这些结果中也可以清楚地看出表面可及性的重要性。(C)2004爱思唯尔有限公司保留所有权利。
A set of nine coal fly ashes, obtained from various US utilities, were fractionated by standard dry-sieving techniques. The carbon contents of the different size fractions were measured, and the nature of the carbon particles was microscopically examined. Significant differences were found in the distribution of carbon in class F and class C ashes. The 'foam index' test is commonly used for quick evaluation of the suitability, with respect to air entrainment, of pozzolanic additives for concrete. This test measures adsorption of air entraining admixtures (AEAs) by the carbon in the fly ash. Application of this test to the different ash fractions confirmed that the smallest particle size fractions of ash make the major contribution to AEA adsorption. The carbon from class F ash has a comparable capacity for AEA adsorption as carbon from class C ash, when compared on a surface area basis. What makes the class C carbons apparently 'worse' is the fact that they have much higher surface areas than class F carbons (and it is only by virtue of the low carbon mass in most class C ashes that problems with these ashes are not more common). The importance of accessibility of the surface is also clearly seen from these results. (C) 2004 Elsevier Ltd. All rights reserved.