Study on the Utilization of FBC Ashes as Cement Admixture

2011 ◽  
Vol 99-100 ◽  
pp. 116-119
Author(s):  
Jing Xiang Liu ◽  
Yuan Ming Song ◽  
Hui Zhong Xu ◽  
Yu Long Ma ◽  
Yu Bo Yue ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Fluidized Bed ◽  
Coal Combustion ◽  
Cement Mortar ◽  
Setting Time ◽  
Pulverized Coal Combustion ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Cement System

Compared with ordinary Pulverized Coal Combustion (PC) fly ashes, Fluidized Bed Combustion (FBC) ashes have some special properties. The effect of FBC ashes content on the strength of cement mortar was studied, and the physical properties of FBC ashes-cement mortar with 30% FBC ashes were also investigated. The results show that the flexural and compressive strength at 7 and 28 days of the mortar gradually decreases with the increase of FBC ashes content. Under the same dosage, the strength of FBC ashes-cement mortar is greater than that of PC fly ashes-cement mortar. The FBC ashes-cement system presents a normal setting time but poor soundness with more than 3.5% SO3. This work confirms that the properties of FBC ashes-cement system are superior to those of PC fly ashes-cement system when SO3 content is no more than 3.5%.

Laboratory evaluation of solid residues from atmospheric fluidized bed combustion systems

1988 ◽  
Vol 15 (1) ◽  
pp. 49-57 ◽  
Author(s):  
T. W. Constable ◽  
R. Kissel ◽  
S. E. Sawell ◽  
W. Cunningham
Keyword(s):  
Fluidized Bed ◽  
Coal Combustion ◽  
Laboratory Evaluation ◽  
Pulverized Coal Combustion ◽  
Leaching Test ◽  
Test Results ◽  
Fluidized Bed Combustion ◽  
Bubbling Bed ◽  
Physical Chemical ◽  
Ash Leaching

Tests and analyses were conducted to characterize the physical, chemical, exothermic, and leaching properties of solid residues from bubbling bed atmospheric fluidized bed combustion units. The residues were produced during the combustion of eastern Canadian high-sulphur bituminous coals (4–8% sulphur) in a bed of eastern Canadian limestone. The residues were highly buffered and composed primarily of calcium and sulphur salts. They were exothermic and swelled considerably when contacted with water. Leachates generated during 20-cycle serial batch leaching tests were highly alkaline with high total dissolved solids concentrations, primarily calcium and sulphate ions. Column leaching test results and field observations suggest reactions may continue to occur over several months until the residues eventually solidify. The residues have properties that are unique, in comparison with conventional pulverized coal combustion wastes. Key words: fluidized bed combustion, ash, leaching.

scholarly journals Circulation Fluidized Bed Combustion Fly Ash as Partial Replacement of Fine Aggregates in Roller Compacted Concrete

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4204 ◽  
Author(s):  
Wei-Ting Lin ◽  
Kae-Long Lin ◽  
Kailun Chen ◽  
Kinga Korniejenko ◽  
Marek Hebda ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Fluidized Bed ◽  
Setting Time ◽  
Unit Weight ◽  
Fluidized Bed Combustion ◽  
Sulfate Resistance ◽  
Roller Compacted Concrete ◽  
Fine Aggregates

Recently, many people around the world have been concerned with environmental protection and sustainability. The goal of various countries’ research has been focused on how to regenerate existing resources. Circulation fluidized bed combustion (CFBC) technology is one of the emerging combustion technologies for electricity generation and produces more than 800,000 tons of CFBC fly ash (CFA) per year for combustion. CFA has been widely applied in cement additive, new building materials and cement-based materials. The goal of this study was to discuss the engineering properties of roller-compacted concrete containing CFA. Test subjects included compressive strength, flexural strength, absorption, setting time, unit weight, sulfate resistance, SEM microscopic observations and XRD ingredient analysis. Test results indicate the following: (1) using CFA as a substitute of fine aggregates up to 10 wt.% would improve the development of later flexural strength; (2) the increases in pre-pressure would increase the compressive strength and unit weight and decrease absorption; (3) using CFA would reduce the initial setting time by 30%–60% and reduce the final setting time by 16%–20%; (4) using CFA would reduce the absorption; (5) using CFA would reduce the unit weight by 0.5%–2.8%, and the increases in pre-pressure would increase the unit weight by about 0.9%–2.1%; (6) CaO in CFA helps to improve sulfate resistance; (7) scanning electron microscopy (SEM) observation shows that the increases in pre-pressure would reduce the pores; and (8) X-ray diffraction (XRD) analysis shows that the inclusion of CFA would increase the content of Ca(OH)2 in concrete.

scholarly journals Influence of Agricultural Waste Ash as Pozzolana on the Physical Properties and Compressive Strength of Cement Mortar

2019 ◽  
Vol 9 (1) ◽  
pp. 29-36
Author(s):  
O. Bagcal ◽  
M. Baccay
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Cement Mortar ◽  
Agricultural Waste ◽  
Setting Time ◽  
Partial Replacement ◽  
Masonry Construction ◽  
Pozzolanic Material ◽  
Mix Proportion ◽  
Increasing Demand

Abstract The increasing demand in cement has inspired researchers in both developed and developing countries around the world to explore and consider alternative materials as partial replacement of cement both in concrete and in mortar. In this study, the influence of agricultural waste, particularly corn cob ash, (CCA) as pozzolanic material or supplementary cementitious material (SCM) on the physical properties and compressive strength of cement mortar was investigated. CCA was used as partial replacement of cement ranging from 0% to 20% by weight at water-cementitious ratio of 0.6 and mix proportion of 1 cementitious: 3 fillers. The physical properties evaluated for the mortar paste were setting time and consistency; and compressive strength of hardened mortar cube. The chemical analysis of CCA was conducted, and results indicated that the CCA used in this study is classified as Class C pozzolana with combined SiO2 + Al2O3 + Fe2O3 of 55.86%. The addition of CCA increases the initial and final setting time. The study also revealed that the addition of CCA in the mortar mix reduces the plasticity or fluidity of the paste. Further, the result indicated that the compressive strength of mortars with CCA decreased as the amount of CCA replacements increased in the mixture. The mortar pastes with varying amount of cement replacements, however, are superior for use as mortar for masonry construction.

scholarly journals Predicting the Compressive Strength of Portland Cement Concretes with the Addition of Fluidized Bed Combustion Fly Ashes from Bituminous Coal and Lignite

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Jacek Śliwiński ◽  
Artur Łagosz ◽  
Tomasz Tracz ◽  
Radosław Mróz ◽  
Jan Deja
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Fluidized Bed ◽  
Bituminous Coal ◽  
Pozzolanic Reaction ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Binder Ratio ◽  
Water Binder Ratio

This paper presents the results of an extensive experimental study on the effect of the addition of two types of fly ash produced during fluidized bed combustion of bituminous coal and lignite, which differ substantially in their chemical and mineral compositions, on the compressive strength of concrete. Concretes with water/binder ratios of 0.65, 0.55 and 0.45 made with CEM I 42.5 R Portland cement and gravel aggregate were tested. The analyzed amounts of fly ash added to the binder were 0, 15% and 30% by weight. Based on the results of compressive strength testing after 28 and 90 days of curing, the relationships with the water/binder ratio and fly ash content in the binder were determined. The fly ashes used were highly active and capable of pozzolanic reaction. The relationships established allow the compressive strength of concretes based on composite cement-fly ash binder to be predicted with sufficient accuracy. The results presented in this study are an important contribution to the knowledge of concretes with combined binders. They have the exploratory value of establishing the dependence of compressive strength at 28 and 90 days on binder composition and water-binder ratio. In addition, they could be used almost directly in practical applications.

Utilization of Circulating Fluidized Bed Combustion (CFBC) Fly Ash and Coal-Fired Fly Ash in Portland Cement

2014 ◽  
Vol 629-630 ◽  
pp. 306-313 ◽  
Author(s):  
Mao Chieh Chi ◽  
Ran Huang ◽  
Te Hsien Wu ◽  
Toun Chun Fou
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Fluidized Bed ◽  
Building Materials ◽  
Circulating Fluidized Bed ◽  
Setting Time ◽  
Fluidized Bed Combustion ◽  
Initial Setting Time ◽  
Cfbc Fly Ash ◽  
Circulating Fluidized Bed Combustion

Circulating fluidized bed combustion (CFBC) fly ash is a promising admixture for construction and building materials due to its pozzolanic activity and self-cementitious property. In this study, CFBC fly ash and coal-fired fly ash were used in Portland cement to investigate the pozzolanic and cementitious characteristics of CFBC fly ash and the properties of cement-based composites. Tests show that CFBC fly ash has the potential instead of cementing materials and as an alternative of pozzolan. In fresh specimens, the initial setting time of mortars increases with the increasing amount of cement replacement by CFBC fly ash and coal-fire fly ash. In harden specimens, adding CFBC fly ash to replace OPC reduces the compressive strength. Meanwhile, CFBC fly ash would results in a higher length change when adding over 30%. Based on the results, the amount of CFBC fly ash replacement cement was recommended to be limited below 20%.

Reactivation Studies on Six Fly Ashes From Commercial CFB Boilers

2005 ◽  
Author(s):  
Y. Wu ◽  
J.-P. Charland ◽  
E. J. Anthony ◽  
L. Jia
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Liquid Water ◽  
Circulating Fluidized Bed ◽  
Absorption Capacity ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Commercial Scale ◽  
Circulating Fluidized Bed Combustion ◽  
So2 Absorption

Six different fly ashes from commercial-scale circulating fluidized bed combustion (CFBC) boilers and the carbon-free residues of these ashes were hydrated with liquid water or steam to determine whether hydration could improve sorbent utilization in these samples under fluidized bed combustion conditions. After hydration, for two fly ashes (FA1 and FA6) and three carbon-free samples (FA2-A, FA3-A and FA6-A), the capacity for taking up SO2 showed limited or medium improvement; however, hydration was evidently ineffective in reactivating the remaining samples. It is believed that the reason samples FA6 and FA6-A show a relatively high improvement in SO2 absorption capacity is that these ashes had a larger particle size than any of the other fly ashes examined here. In general, even for these “reactivatable” fly ashes, reactivation by hydration with either liquid water or steam appeared far less promising than for bed ashes, which have been shown to exhibit significant improvement in sulphur capture during re-sulphation. Hydration, whether by steam or liquid water, is not recommended for fly ash, which has a very limited residence time in the boiler due to its small particle size and instead this paper recommends alternative strategies.

scholarly journals Solidification of Municipal Solid Waste Incineration Fly Ash through Co-Mechanical Treatment with Circulation Fluidized Bed Combustion Fly Ash

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 141
Author(s):  
Zhengzhen Yao ◽  
Zhonghui Xu ◽  
Qin Shuai ◽  
Xiaoyue Chen ◽  
Zao Jiang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Fluidized Bed ◽  
Mechanical Treatment ◽  
Waste Incineration ◽  
Municipal Solid Waste Incineration ◽  
Fluidized Bed Combustion ◽  
Waste Incineration Fly Ash

This study aims to explore the solidification performance of municipal solid waste incineration fly ash (MSWIFA) through co-mechanical treatment with circulation fluidized bed combustion fly ash (CFBCFA). The mineral characterization, physical properties, and leaching resistance of the solidified bodies are investigated by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry-differential thermal analysis (TG-DTA), compressive strength, porosity, and leaching test, respectively. C–S–H, ettringite (AFt), and Friedel’s salt (FS) are the predominant hydrate products in the CFBCFA based solidified bodies, which are similar to the cement based solidified bodies. However, CFBCFA based solidified bodies exhibit higher compressive strength (36.7 MPa) than cement based solidified bodies (11.28 MPa), attributing to the three reasons: lower porosity and more compact internal structure of CFBCFA based solidified bodies; large amounts of Ca(OH)2 originating from MSWIFA are conducive to promoting the hydration reaction extent and compressive strength of the CFBCFA based solidified bodies; excessive Ca(OH)2 would cause compressive strength deterioration for the cement based solidified bodies. The heavy metals (Zn, Cu, Cr, Cd, and Pb) concentrations in the extraction solution of the CFBCFA based solidified bodies are far below the requirements of Chinese National Standard GB 5085.3-2007. The solidification of MSWIFA through co-mechanical treatment could be an ideal substitute for cement solidification technology.

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