Fly Ash Containing Alkali Activated Geopolymer Concrete: Effect of the Na2SiO3:NaOH Ratio and Temperature

2018 ◽  
Vol 67 (3) ◽  
pp. 24-29
Author(s):  
Ritwik Sarkar ◽  
S. P. Routray
2021 ◽  

Concrete is the most versatile, durable and reliable material and is the most used building material. It requires large amounts of Portland cement which has environmental problems associated with its production. Hence, an alternative concrete – geopolymer concrete is needed. The general aim of this book is to make significant contributions in understanding and deciphering the mechanisms of the realization of the alkali-activated fly ash-based geopolymer concrete and, at the same time, to present the main characteristics of the materials, components, as well as the influence that they have on the performance of the mechanical properties of the concrete. The book deals with in-depth research of the potential recovery of fly ash and using it as a raw material for the development of new construction materials, offering sustainable solutions to the construction industry.


Activated Slag (AAS) and Fly Ash (FA) based geopolymer concrete a new blended alkali-activated concrete that has been progressively studied over the past years because of its environmental benefits superior engineering properties. Geopolymer has many favorable characteristics in comparison to Ordinary Portland Cement. Many base materials could be utilized to make geopolymer with the convenient concentration of activator solution. In this study, the experimental program composed of two phases; phase on divided into four groups; Group one deliberated the effect of sodium hydroxide molarity and different curing condition on compressive strength. Group two studied the effect of alkali activated solution (NaOH and Na2SiO3) content on compressive strength and workability. The effect of sand replacement with slag on compressive strength and workability was explained in group three. Group four studied the effect of slag replacement with several base materials Fly Ash (FA), Ordinary Portland Cement (OPC), pulverized Red Brick (PRB), and Meta Kaolin (MK). Phase two contains three mixtures from phase one which had the highest compressive strength. For each mixture, the fresh concrete test was air content. In addition the hardened concrete tests were the compressive strength at 3, 7, 28, 90, 180, and 365 days, the flexural strength at 28, 90, and 365 days, and the young's modulus at 28, 90, and 365 days. Moreover; the three mixtures were exposed to elevated temperature at 100oC, 300oC, and 600oC to study the effect of elevated temperature on compressive and flexural strength.


2019 ◽  
Vol 289 ◽  
pp. 11001 ◽  
Author(s):  
Adrian Lăzărescu ◽  
Călin Mircea ◽  
Henriette Szilagyi ◽  
Cornelia Baeră

As concrete demand is constantly increasing in recent years and also considering that cement production is both a consumer of natural resources and a source of carbon dioxide release into the atmosphere, there have been worldwide investigations into green alternatives for making concrete environmentally friendlier and simultaneously to satisfy the development of infrastructure facilities. The use of fly ash as a component of cementitious binders is not new but when considering the specific case of alkaline activation and fly ash representing the only source for the binder formation, it necessitates a more complete understanding of its specific reactions during the alkaline activation process. Since the fly ash varies dramatically, not only from one source to another, but also from one batch to another even when provided by the same power plant, its chemistry in obtaining alkali-activated materials during the geopolymerisation process and the final mechanical properties are considered crucial for the performance of geopolymer concrete. This paper will provide a review of the experimental results concerning the physical and mechanical evaluation of the alkali-activated fly ash-based geopolymer materials, developed with different types of fly ash, for a better understanding of geopolymer concrete production control.


Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 11
Author(s):  
Adrian-Victor Lăzărescu ◽  
Henriette Szilagyi ◽  
Cornelia Baeră ◽  
Andreea Hegyi

Current research and development policies in the field of building materials, in the context of sustainable development, have the main objectives of increasing the safety and performance of the built environment at the same time as reducing pollution and its negative impact. Today, the idea that the sustainable city of the future should meet human needs and maintain a higher quality of life is worldwide unanimously accepted. The aim of this paper is to present results regarding the production of alkali-activated fly ash-based geopolymer concrete, a new, alternative material, produced using local available raw materials from Romania.


2021 ◽  
Vol 7 (6) ◽  
pp. 1036-1049
Author(s):  
Gautam Kumar ◽  
S. S. Mishra

This paper focuses on the development of a concrete material by utilizing fly ash and blast furnace slag in conjunction with coarse and fine aggregates with an aim to reduce pollution and eliminate the use of energy extensive binding material like cement. Alternative binding materials have been tried with an aim to get rather an improved concrete material. Alkali-Activated Solution (AAS) made of the hydroxide and silicate solutions of sodium was adopted as the liquid binder whereas, Class F” fly ash and Ground Granulated Blast Furnace Slag (GGBFS) mixed in dry state were used as the Geopolymer Solid Binder (GSB). The liquid binder was used to synthesize the solid binder by thermal curing. The paper investigates the use, influence and relative quantities of the liquid and solid binders in the development of the alkali-activated GGBFS based Geopolymer Concrete (GPC). Varying ratios of AAS to GSB were taken to assess their optimum content. Further, different percentages of GGBFS were used as a partial replacement of Class F fly ash to determine the optimum replacement of GGBFS in the GPC. In order to assess their effects on various properties test samples of cubes, cylinders and beams were cast and tested at 3, 7, and 28 days. Thermal curing of GPC has also resorted for favorable results. It was found that AAS to GSB ratio of 0.5 and GGBFS content of 80% yielded the maximum strength with a little unfavorable effect on workability. The overall results indicated that AAS and GGBFS offer good geopolymer concrete which will find its applicability in water scarce areas. Doi: 10.28991/cej-2021-03091708 Full Text: PDF


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