Improvement of the early and final compressive strength of fly ash-based geopolymer concrete at ambient conditions

被引:83
作者
Assi, Lateef [1 ]
Ghahari, SeyedAli [2 ]
Deaver, Edward [3 ]
Leaphart, Davis [4 ]
Ziehl, Paul [5 ]
机构
[1] Univ South Carolina, Dept Civil & Environm Engn, 300 Main St,B122A, Columbia, SC 29208 USA
[2] Purdue Univ, Sch Civil Engn, 550 Stadium Mall Dr,HAMP G175, W Lafayette, IN 47907 USA
[3] Holcim US Inc, 9624 Bailey Rd,Suite 275, Cornelius, NC 28031 USA
[4] 100 Maple Shade Ln, Lexington, SC 29037 USA
[5] Univ South Carolina, Dept Civil & Environm Engn, 300 Main St,C206, Columbia, SC 29208 USA
关键词
Geopolymer concrete; Alkali activated fly ash concrete; Early compressive strength; Partial Portland cement replacement; Activating solution based silica fume; SODIUM;
D O I
10.1016/j.conbuildmat.2016.07.069
中图分类号
TU [建筑科学];
学科分类号
0813 ;
摘要
Sustainable concrete has reduced CO2 emissions, is durable, and is expected to have less detrimental effect on future generations, due to the fact that it utilizes waste materials. However, the need for external heat limits construction applications. The effects of sodium hydroxide ratio, external heat amount, and partial Portland cement replacement on fly ash-based geopolymer concrete were investigated. The early compressive strength, density, absorption, and permeable voids were measured; and the microstructure of the fly ash-based geopolymer paste was observed and characterized. The activating solution was a combination of silica fume, sodium hydroxide, and water. Experimentation showed that application of external heat plays a major role in compressive strength. Results also show that early and final compressive strength gains, in case of absence of external heat, can be improved by using Portland cement as a partial replacement of fly ash. The Scanning Electron Microscopy (SEM) results showed that the addition of Portland cement utilized the free water from the geopolymerization reaction. It not only led to a reduction in the microcracks formation due to less shrinkage, but also provided extra alkalinity, such as calcium hydroxide, which helped accelerate the fly ash and the activating solution reaction. Additionally, the permeable void ratio is affected by the Portland cement replacement, showing a significant reduction when the Portland cement ratio is increased. (C) 2016 Elsevier Ltd. All rights reserved.
引用
收藏
页码:806 / 813
页数:8
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