Effect of slag, silica fume, and metakaolin on properties and performance of alkali-activated fly ash cured at ambient temperature
Effect of slag, silica fume, and metakaolin on properties and performance of alkali-activated fly ash cured at ambient temperature
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DOI：
10.1016/j.conbuildmat.2018.11.172
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发表时间：
2019-02-10
影响因子：
7.4
通讯作者：
Kim, Yong-Rak
中科院分区：
文献类型：
--
作者：
Alanazi, Hani;Hu, Jiong;Kim, Yong-Rak
碱激发飞灰(AAFA)通常在高温下养护，限制了其广泛的应用。然而，一些研究表明，加入不同的胶凝添加剂可以显著改善常温养护的AAFA的性能。研究了在常温养护条件下，用矿渣、偏高岭土和硅灰等不同潜在胶凝添加剂替代少量粉煤灰对AAFA混合料各项性能的影响。为此，进行了工作性、地聚合热释放、抗压强度、杨氏模量、电阻率、氯离子渗透性和孔结构分布等实验观察。研究了碱液浓度与不同化学成分组合对力学性能和渗透率特性的影响。一种普通的波特兰水泥也包括在测试计划中，作为比较参考。试验结果表明，与普通硅酸盐水泥混合料相比，AAFA混合料具有较低的放热性能，其放热结果与早期强度发展规律一致。偏高岭土的加入使胶凝材料的早期强度和硬度有了显著的提高。矿渣的掺入改善了常温养护AAFA的力学性能和渗透性能，矿渣的掺入对硅酸钠(SS)和氢氧化钠(SH)溶液比例的影响更大。在AAFA混合料中加入硅灰降低了材料的力学性能，增加了大毛细气孔的体积百分比。(C)2018爱思唯尔有限公司。保留所有权利。
Alkali-activated fly ash (AAFA) is usually cured at elevated temperature, which limits its wide field applications. However, several studies have shown that properties of AAFA cured at ambient temperature can be significantly improved by incorporating different cementitious additives. This research investigated the impact of substituting a small portion of fly ash with different potential cementitious additives such as slag, metakaolin, and silica fume on various properties of AAFA mixtures at ambient curing conditions. Toward that end, several experimental observations including workability, geopolymerization heat released, compressive strength, Young's modulus, electrical resistivity, chloride permeability, and pore structure distribution were made. The effects of alkaline solution concentration combined with the different chemical compositions on mechanical properties and permeability characteristics were also investigated. An ordinary Portland cement was also included in the testing program as a comparative reference. Test results showed that the AAFA mixtures exhibited lower heat as compared to ordinary Portland cement mixture, and the results of heat evolution were in line with early-age strength development. The inclusion of metakaolin resulted in a significant improvement in the early strength and stiffness. The inclusion of slag led to the improvement of the mechanical and permeability properties of AAFA cured at ambient temperature, and the effect of sodium silicate (SS) to sodium hydroxide (SH) solution ratio was found to be more profound when the slag was used as an additive. Incorporating silica fume in the AAFA mixtures decreased the mechanical properties and increased the volumetric percentage of large capillary pores. (C) 2018 Elsevier Ltd. All rights reserved.