Engineering behaviour of a low carbon, pozzolanic fly ash and its potential as a construction fill

1991 ◽  
Vol 28 (4) ◽  
pp. 542-555 ◽  
Author(s):  
B. Indraratna ◽  
P. Nutalaya ◽  
K. S. Koo ◽  
N. Kuganenthira
Keyword(s):  
Fly Ash ◽  
Pozzolanic Activity ◽  
Unburned Carbon ◽  
Low Carbon ◽  
Collapse Potential ◽  
Pozzolanic Reactivity ◽  
Wide Range ◽  
Good Potential ◽  
Class C ◽  
Mae Moh

Detailed laboratory investigations were conducted on Mae Moh fly ash from northern Thailand for the determination of its grain size distribution, mineralogy, pozzolanic activity, compaction and strength characteristics, and the collapse potential. On the basis of the experimental results, this fly ash is classified as ASTM class C, which is considered to be pozzolanic. It has good potential to be utilized as an effective fill for embankments (roads and dams), airfields, pavements, and building bricks, as well as for the stabilization of compressible or erodible foundations. Because of the fact that Mae Moh fly ash contains only a negligible amount of unburned carbon, its pozzolanic reactivity is accelerated, in comparison with the relatively inert, high-carbon fly ash produced elsewhere in Thailand and many other parts of Asia. It is also demonstrated that Mae Moh fly ash can be easily compacted to produce acceptable dry densities over a wide range of water contents. Curing with an adequate moisture supply in the presence of calcium oxide plays an important role in accelerating the pozzolanic reactions, hence improving the time-dependent-properties. This study further proposes that a curing period of 2–3 weeks is sufficient for this material to approach its maximum strength. Although the behaviour of one specific fly ash cannot generalize the wide array of other ashes, the test results obtained for Mae Moh fly ash may be applied to lignite ashes in the category of ASTM class C. Key words: fly ash, structural fill, compaction, compressive strength, shear strength, collapse potential, pozzolanic activity.

Effect of Silica to Alumina Ratio on the Compressive Strength of Class C Fly Ash-Based Geopolymers

2015 ◽  
Vol 659 ◽  
pp. 80-84 ◽  
Author(s):  
Patthamaporn Timakul ◽  
Kanyarat Thanaphatwetphisit ◽  
Pavadee Aungkavattana
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Curing Temperature ◽  
Infrared Study ◽  
Xrd Study ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Solid Part ◽  
Class C ◽  
Mae Moh

This study investigated the effect of silica to alumina ratio on the compressive strength of geopolymer. The high calcium fly ash (Class C, ASTM 618) wastes from Mae Moh Thailand power plant, which is SiO2 (30.97%) and Al2O3 (17.16%)-rich materials was employed as the main solid part to prepare geopolymers, apart from kaolinite. The combination of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) solution, and distilled water as 1:1:4 mass ratios were used as the liquid activator. The curing temperature in the oven was fixed at 75oC and varied curing time for 24, 48, 72 and 96 hours. Further curing was done at room temperature for 28 days before characterizations. XRD study of synthesized geopolymers showed a hump of not well-defined peaks and some major peaks of quartz, and unreacted kaolinite indicating the incomplete geopolymerization reaction. Infrared study showed the Al-O-Si and Si-O-Si bonds in all geopolymers samples. The compressive strength of geopolymer increased from 32 to 40 MPa when the ratio of SiO2 : Al2O3 was increased from 2.60 to 2.65. However, the compressive strength was decreased after increasing the SiO2 : Al2O3 ratio from 2.65 to 3.0. The highest compressive strength was found when the SiO2 : Al2O3 ratio was 2.65 with the curing condition at 75oC for 96 h which the samples also possessed high density.

Experimental Study on Classification of High Carbon Fly Ash with a Hydrocyclone

2014 ◽  
Vol 955-959 ◽  
pp. 2779-2784
Author(s):  
Sheng Bing Zhang ◽  
Yi Liu ◽  
Yan Hong Zhang ◽  
Hua Lin Wang
Keyword(s):  
Fly Ash ◽  
Classification Performance ◽  
Raw Material ◽  
Unburned Carbon ◽  
Flotation Column ◽  
Wide Range ◽  
Large Particles ◽  
Good Classification Performance

The fly ash has a wide range of particles size and has a large amount of unburned carbon. As a raw material, the presence of the large particles and the unburned carbon will reduce the quality of the product. How to improve the utilization of fly ash has become one of focus points. In this work, hydrocyclone was adopted for classification after decarburization in a flotation column. Hydrocyclone showed a very good classification performance. In overflow, the particles were all smaller than 85μm. About 97.34% of the particles were smaller than 25 μm. Different fly ash content was selected to investigate its influence on the decarburization. The results showed that it made no obvious differences.

scholarly journals Beneficiated ponded fly ash for concretes with high volume mineral additions

2020 ◽  
Vol 315 ◽  
pp. 07006
Author(s):  
Nikolai Zaichenko ◽  
Irina Petrik ◽  
Liudmila Zaichenko
Keyword(s):  
Fly Ash ◽  
High Volume ◽  
High Rate ◽  
Unburned Carbon ◽  
Strength Increase ◽  
Low Carbon ◽  
Cement Pastes ◽  
Technical Requirements ◽  
Mineral Additions ◽  
High Level

The article presents the investigation results of effect of beneficiated ponded fly ash on the properties of cement pastes and concretes with high-level replacement of Portland cement. To improve the characteristics of ponded fly ash meeting technical requirements for replacing cement in concrete the triboelectrostatic beneficiation technology has been elaborated. This technology can produce low-carbon ash product (LOI = 2.52 % in this study) for the high replacing level of cement (45 %) in concretes. The beneficiated ponded fly ash has an improved granulometric and phase composition, a decreased content of unburned carbon that accelerates the hydration process of cement, increases the rheological properties of cement paste and the ability of air-entraining admixture to hold the required involved air. In a combination with the nanostructured-carbon-based plasticizing admixture the beneficiated ponded fly ash exhibits high rate of strength increase when is used in high-volume fly ash concretes.

scholarly journals Optimization of Low-Carbon Footprint Quaternary and Quinary (37% Fly Ash) Cementitious Nanocomposites with Polycarboxylate or Aqueous Nanosilica Particles

2019 ◽  
Vol 2019 ◽  
pp. 1-26 ◽  
Author(s):  
Styliani Papatzani ◽  
Kevin Paine
Keyword(s):  
Fly Ash ◽  
Carbon Footprint ◽  
Limestone Powder ◽  
Low Carbon ◽  
Hydration Products ◽  
X Ray ◽  
Pozzolanic Reactivity ◽  
Nanosilica Particles ◽  
Electron Imaging ◽  
Scanning Electron

The dispersion medium of nano-SiO2 (nS) particles can have a significant effect on the properties of nanoparticles themselves and consequently on the cement binders it will be added to. In this paper, nS particles dispersed in (a) polycarboxylate or (b) water were added to a low-carbon footprint reference binder containing 43% Portland cement (PC), 20% limestone powder (LS), and 37% fly ash (FA) by mass of binder. Eight quaternary binders containing nS, PC, LS, and FA and eight quinary binders comprising nS, PC, LS, FA, and silica fume (μS) were investigated. nS was added at 0.1%, 0.2%, 0.5%, or 1.0% by mass of binder as a replacement of LS for the quaternary binders and at 0.5% or 1.0% for the quinary binders. The nanoparticles were examined via transmission and X-ray scanning electron microscopy (TEM/SEM/EDX). For the pastes, compressive strength tests and thermal gravimetric analyses (TGAs) were performed at days 1, 7, 28, and 56, all testified to additional pozzolanic activity and additional C–S–H production. X-ray diffraction analyses and backscattered scanning electron imaging carried out on specific formulations also confirmed this finding at days 1, 28, and 56. Notwithstanding the additional pozzolanic reactivity, nS particles could not mitigate the delayed hydration of the reference paste in the early ages. In such complex formulations, the hydration products seem to create a wrapping around the FA particles delaying their activation at early ages. At later ages, the 0.5% nS addition provided strength, microstructural, and hydration improvements. The polycarboxylate/nS particles provided more pronounced strength improvements at 0.5% addition, possibly due to their superplasticizing effect. Lastly, a tabulated literature review on the thermal decomposition ranges of the hydration products of cementitious nanocomposites is also presented.

Precipitation at the transformation interface of pearlite in steel

1990 ◽  
Vol 48 (4) ◽  
pp. 912-913
Author(s):  
F. A. Khalid ◽  
D. V. Edmonds
Keyword(s):  
Thin Foil ◽  
Carbon Steels ◽  
Model Alloy ◽  
Low Carbon ◽  
High Carbon ◽  
Growth Interface ◽  
Medium Carbon ◽  
Interphase Precipitation ◽  
Solution Treated ◽  
Wide Range

The austenite/pearlite growth interface in a model alloy steel (Fe-1lMn-0.8C-0.5V nominal wt%) is being studied in an attempt to characterise the morphology and mechanism of VC precipitation at the growth interface. In this alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the precipitation of VC at the austenite/ferrite interface, which reaction, termed interphase precipitation, occurs in a number of low- carbon HSLA and microalloyed medium- and high- carbon steels. Some observations of interphase precipitation in microalloyed low- and medium- carbon commercial steels are also reported for comparison as this reaction can be responsible for a significant increase in strength in a wide range of commercial steels.The experimental alloy was made as 50 g argon arc melts using high purity materials and homogenised. Samples were solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised at 1300 °C for 15 min. and isothermally transformed at 620 °C for 10-18hrs. and WQ. Specimens of microalloyed commercial steels were studied in either as-rolled or as- forged conditions. Detailed procedures of thin foil preparation for TEM are given elsewhere.

SAE 1020

Alloy Digest ◽  
1987 ◽  
Vol 36 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Heat Treating ◽  
Low Carbon ◽  
Steel Mills ◽  
Temperature Performance ◽  
Wide Range ◽  
Cold Worked

Abstract SAE 1020 is a low-carbon steel combining good machinability, workability and weldability. It is carburized for use in case-hardened components and it is used for a wide range of applications in the hot-worked, cold-worked, normalized or quenched-and-tempered conditions. Its many uses include bolts, rods, plate applications, machinery components, case-hardened parts, spinning tools and trimming dies. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on low temperature performance and corrosion resistance as well as heat treating, machining, joining, and surface treatment. Filing Code: CS-113. Producer or source: Carbon steel mills.

A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland

2001 ◽  
pp. 159-166 ◽  
Author(s):  
Jens Konnerup-Madsen
Keyword(s):  
Nepheline Syenite ◽  
Subsequent Development ◽  
High Water ◽  
Vapour Phase ◽  
Low Carbon ◽  
Low Oxygen ◽  
Alkaline Complex ◽  
Hydrocarbon Gases ◽  
Wide Range ◽  
Water Contents

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Konnerup-Madsen, J. (2001). A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 159-166. https://doi.org/10.34194/ggub.v190.5187 _______________ Fluid inclusions in minerals from agpaitic nepheline syenites and hydrothermal veins in the Ilímaussaq complex and in similar agpaitic complexes on the Kola Peninsula, Russia, are dominated by hydrocarbon gases (predominantly methane) and hydrogen. Such volatile compositions differ considerably from those of most other igneous rocks and their formation and entrapment in minerals reflects low oxygen fugacities and a wide range of crystallisation temperatures extending to a low-temperature solidus. Their composition reflects initial low carbon contents and high water contents of the magma resulting in the exsolution of a waterrich CO2–H2O dominated vapour phase. Fractionation of chlorides into the vapour phase results in high salinities and the subsequent development of a heterogeneous vapour phase with a highly saline aqueous-rich fraction and a methane-dominated fraction, with preferential entrapment of the latter, possibly due to different wetting characteristics. The light stable isotope compositions support an abiogenic origin for the hydrocarbons in agpaitic nepheline syenite complexes.

"Recent Patents on the Triboelectrostatic Separation of Fly Ash"

2019 ◽  
Vol 13 ◽  
Author(s):  
Haisheng Li ◽  
Wenping Wang ◽  
Yinghua Chen ◽  
Xinxi Zhang ◽  
Chaoyong Li
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
High Efficiency ◽  
Separation Efficiency ◽  
High Reliability ◽  
Operating Conditions ◽  
Security Requirements ◽  
Unburned Carbon ◽  
Efficient Operation ◽  
Triboelectrostatic Separation

Background: The fly ash produced by coal-fired power plants is an industrial waste. The environmental pollution problems caused by fly ash have been widely of public environmental concern. As a waste of recoverable resources, it can be used in the field of building materials, agricultural fertilizers, environmental materials, new materials, etc. Unburned carbon content in fly ash has an influence on the performance of resource reuse products. Therefore, it is the key to remove unburned carbon from fly ash. As a physical method, triboelectrostatic separation technology has been widely used because of obvious advantages, such as high-efficiency, simple process, high reliability, without water resources consumption and secondary pollution. Objective: The related patents of fly ash triboelectrostatic separation had been reviewed. The structural characteristics and working principle of these patents are analyzed in detail. The results can provide some meaningful references for the improvement of separation efficiency and optimal design. Methods: Based on the comparative analysis for the latest patents related to fly ash triboelectrostatic separation, the future development is presented. Results: The patents focused on the charging efficiency and separation efficiency. Studies show that remarkable improvements have been achieved for the fly ash triboelectrostatic separation. Some patents have been used in industrial production. Conclusion: According to the current technology status, the researches related to process optimization and anti-interference ability will be beneficial to overcome the influence of operating conditions and complex environment, and meet system security requirements. The intelligent control can not only ensure the process continuity and stability, but also realize the efficient operation and management automatically. Meanwhile, the researchers should pay more attention to the resource utilization of fly ash processed by triboelectrostatic separation.

Fly ash as a raw material for low-carbon cement clinkers and its radiological properties

2021 ◽  
Author(s):  
Miljana Mirković ◽  
Ljiljana Kljajević ◽  
Snežana Nenadović ◽  
Sabina Dolenec ◽  
Katarina Šter ◽  
...  
Keyword(s):  
Fly Ash ◽  
Raw Material ◽  
Low Carbon ◽  
Cement Clinkers ◽  
Radiological Properties

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

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