Alkali Activation of Fly Ash in the Presence of Sodium Nitrate

2021 ◽  
Author(s):  
Ela Ofer-Rozovsky ◽  
Gabriela Bar-Nes ◽  
Amnon Katz ◽  
Michal Arbel Haddad
Keyword(s):  
Fly Ash ◽  
Agricultural Runoff ◽  
Nuclear Industry ◽  
Alkali Activation ◽  
Waste Streams ◽  
Promoting Effect ◽  
Crystalline Phases ◽  
Waste Immobilization ◽  
High Alkalinity ◽  
Formation And Evolution

Abstract The use of fly ash as a precursor for geopolymer has been investigated during the last decades for various applications. The aim of this research was to study the effect of nitrate on the formation and evolution of fly ash-based geopolymers, in order to assess their applicability as waste immobilization matrices. These may be of interest in order to treat waste streams from agricultural runoff and various industries including the nuclear industry. Fly ash was alkali-activated using NaOH solutions of various alkalinities, to which nitrates were added as NaNO3. The samples were cured at 40֯C for different periods and characterized by X-Ray diffractometry, Fourier transform mid-Infrared spectroscopy, scanning electron microscopy (SEM), and compressive strength measurements. The content of neo-formed crystalline phases in fly ash-based geopolymers was found to be lower than in metakaolin-based systems studied previously. The nature of the minerals formed in nitrate-free samples differed from those obtained in corresponding metakaolin-based geopolymers. Nevertheless, the dominant phase formed in the presence of nitrate at sufficiently high alkalinity was nitrate-cancrinite, as reported for metakaolin-based geopolymers, regardless of the type of fly-ash used. Although the presence of nitrates was found to have a promoting effect on the geopolymerization process of metakaolin-based geopolymers, it was found to inhibit the processes in fly-ash-based geopolymers.The formation of crystalline phases in FA-based geopolymers suggests that these materials may be used for immobilizing various hazardous species, while FA-based geopolymers containing the nitrate-cancrinite can be considered as a promising candidate for immobilizing radionuclides from radioactive wastes.

Lightweight Fly Ash-Based Geopolymer Concrete

2012 ◽  
Vol 626 ◽  
pp. 781-785 ◽  
Author(s):  
A. Abdulkareem Omar ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin ◽  
I. Khairul Nizar
Keyword(s):  
Fly Ash ◽  
Lightweight Aggregate ◽  
Synthesis Process ◽  
Dry Density ◽  
Alkali Activation ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Mix Proportioning ◽  
Geopolymer Matrix ◽  
High Alkalinity

The experiments of this study were preformed to study the synthesis process for lightweight aggregate geopolymer concrete (LWAGC) using normal sand as a fine aggregate and expanded clay as lightweight aggregate. The LWAGC was synthesized by the alkali activation of a fly ash (FA) as the source material by mixture of liquid alkaline activator. The resultant LWAGC possessed a compressive strength of 18.86 MPa at age of 28 days with oven-dry density of 1438.7 kg/m3.The microstructure images showed that the high alkalinity chemical reaction of the geopolymerization process does not react with the used aggregate, and the smooth surface of the aggregate declined the interaction between the geopolymer matrix and aggregate. The significant result of the current study was the proven of the reliability of the ACI 211.2-98 standard used for designing and mix proportioning of OPC lightweight aggregate structural concrete in the production of LWAGC.

Alkali activation of biomass fly ash–metakaolin blends

Fuel ◽  
2012 ◽  
Vol 98 ◽  
pp. 265-271 ◽  
Author(s):  
Rejini Rajamma ◽  
João A. Labrincha ◽  
Victor M. Ferreira
Keyword(s):  
Fly Ash ◽  
Alkali Activation ◽  
Biomass Fly Ash

Alkali activation of fly ash: Effect of the SiO2/Na2O ratio

2007 ◽  
Vol 106 (1-3) ◽  
pp. 180-191 ◽  
Author(s):  
M. Criado ◽  
A. Fernández-Jiménez ◽  
A. Palomo
Keyword(s):  
Fly Ash ◽  
Alkali Activation

Phase evolution of fly ash calcium constituent at early alkali activation reaction age

2016 ◽  
Vol 174 ◽  
pp. 175-179 ◽  
Author(s):  
Ningning Shao ◽  
Ze Liu ◽  
Jianjun Fan ◽  
Yu Zhou ◽  
Dongmin Wang
Keyword(s):  
Fly Ash ◽  
Phase Evolution ◽  
Alkali Activation ◽  
Activation Reaction

Investigation on Thermal Stability of Geopolymer Based Zeolite in Fire Case Study

2020 ◽  
Vol 1009 ◽  
pp. 31-36
Author(s):  
Kanokwan Kanyalert ◽  
Prinya Chindaprasirt ◽  
Duangkanok Tanangteerapong
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Alkali Activation ◽  
Different Types ◽  
Temperature Exposure ◽  
In Fire ◽  
Thermal Stability Of

This work aims to reveal the effects of zeolite on properties of fly ash based geopolymer under high temperature at 300 °C, 600 °C and 900 °C. The specimens were prepared by alkali activation of fly ash, which was partially replaced by two different types of zeolite at 10%, 20% and 30% by weight. The specimens were analyzed for the maximum compressive strength, weight loss percentage, XRD and SEM. The results highlighted that the percentage of weight loss increased with the ratio of zeolite replacement. The compressive strength of geopolymer with synthetic zeolite and natural zeolite at 7, 28, 60 days were similar. The high-temperature exposure resulted in the reduction in compressive strength in all proportions. At the same temperature, compressive strength of all specimens were not significantly different.

Alkali activation of fly ash. Part III: Effect of curing conditions on reaction and its graphical description

Fuel ◽  
2010 ◽  
Vol 89 (11) ◽  
pp. 3185-3192 ◽  
Author(s):  
M. Criado ◽  
A. Fernández-Jiménez ◽  
A. Palomo
Keyword(s):  
Fly Ash ◽  
Alkali Activation ◽  
Curing Conditions

Measuring Graphitic Carbon and Crystalline Minerals in Coals and Bottom Ashes

1987 ◽  
Vol 31 ◽  
pp. 343-349 ◽  
Author(s):  
David L. Wertz ◽  
Leo W. Collins ◽  
Franz Froelicher
Keyword(s):  
Energy Source ◽  
Fly Ash ◽  
Chemical Species ◽  
Primary Energy ◽  
Toxic Chemical ◽  
Atom Pair ◽  
Crystalline Phases ◽  
X Ray ◽  
X Ray Scattering ◽  
Lignite Fly Ash

AbstractThe use of coal, as either a primary energy source or as a source of feedstock chemicals, has been complicated by the noxious and toxic chemical species formed in its gaseous effluents and also by the huge quantities of ash vhich result from its processing. Both the noxious gases and the ash have been the subjects of Federal legislations.X-ray powder patterns (XRPP), composed of atom-pair and self x~ray scattering and the diffraction produced by crystalline phases, have long been used to investigate coals and particularly their combustion ashes (1-3). Over twenty different crystalline phases have recently been reported to exist in certain lignite fly ash (3). Analysis of the crystalline phases has typically been emphasized in previous papers involving coals and ashes, but the amorphous scattering has been given little treatment.

Semi-Quantitative XRD Analysis of Fly Ash Using Rutile as an Internal Standard

1988 ◽  
Vol 32 ◽  
pp. 569-576 ◽  
Author(s):  
A. Thedchanamoorthy ◽  
G.J. McCarthy
Keyword(s):  
Fly Ash ◽  
Error Analysis ◽  
North American ◽  
Intensity Ratio ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Xrd Analysis ◽  
X Rays ◽  
Fly Ashes ◽  
Crystalline Phases

AbstractXRD analysis of fly ash was quantitated using the Reference Intensity Ratio (RIR) method and rutile (TiO2) as an internal standard. Rutile RIR's for 15 of the crystalline phases commonly observed in North American fly ash were determined. Error analysis on the various steps in quantitation indicated that precision ranged from ±10% of the amount present for phases that diffract x-rays strongly to ±21% for weakly diffracting phases. Limit of detection in the mostly glassy fly ashes ranged from 0.2% for lime, the most strongly diffracting phase, to 3.5% for weakly diffracting mullite. Accuracy evaluated with a simulated fly ash was within the limits established by precision, but in actual fly ash samples, accuracy will be a function of the match between the crystallinity and composition of the analyte and the analyte standard. Overlaps among peaks of some of the important phases require intensity proportioning; for this reason, the method is best described as semi-quantitative.

Investigation to some Preliminary Geotechnical Properties of Soft Clay Stabilized by Fly Ash Based Geopolymers

2020 ◽  
Vol 857 ◽  
pp. 259-265
Author(s):  
Jasim M. Abbas ◽  
Amer M Ibrahim ◽  
Abdalla M. Shihab
Keyword(s):  
Fly Ash ◽  
Specific Gravity ◽  
Soft Clay ◽  
Cost Effective ◽  
Geotechnical Properties ◽  
Experimental Program ◽  
Dry Density ◽  
Alkali Activation ◽  
Plastic Behavior ◽  
Maximum Dry Density

The civil engineering projects that includes soft clay within its activities has a serious concern of hazards, such hazards can be overcame by treating the existing soils by certain materials which are named as "stabilizers". The common materials that are highly used in this field are ordinary Portland cement, fly ash, lime and rice husk ash, etc. Each one of these stabilizers has its known shortcomings. The alkali activation of any alumina silicate source produces some kind of cost effective primary binding gel which is known as "Geopolymers". This study is devoted to investigate the role of liquid over fly ash ratio to some soil – FA based Geopolymers geotechnical properties. Such ratio is taken as 2.71, 3.167, 3.8 and 4.75 respectively within the experimental program and the investigated geotechnical properties are the specific gravity, liquid and plastic limit, compaction characteristics and California bearing ratio. The tests results showed that the maximum dry density decreased about 42 % at 2.71 liq/FA whereas this the specific gravity decreased 27 % at the same this ratio. In addition, the 3.8 and 4.75 of such limits revealed no plastic behavior due to the high presence of liquid.

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