Elimination of Negative Influence of Fluidized Bed Combustion Fly Ash on Viscosity of Cement Mix

2016 ◽  
Vol 865 ◽  
pp. 12-16 ◽  
Author(s):  
Martin Ťažký ◽  
Rudolf Hela
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Negative Impact ◽  
Negative Influence ◽  
Fluidized Bed Combustion ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Variable Chemical ◽  
Negative Feature ◽  
Cement Mixture

Use of fluidized bed combustion fly ash as an admixture for manufacture of cement based composite materials is not quite common now, however, there are real ways of utilizing its potential. The most important negative feature of this fly ash is its variable chemical composition, which supports formation of new forms growing within the structure with negative impact of durability of the composite material. The morphology of this type of fly ash is also not very favorable as it has negative influence on consistency. Fluidized bed combustion fly ash considerably deteriorates consistency of cement mixture, which results in higher water-cement ratio and consequently worsening of physico-mechanical and durability parameters of the whole composite. Therefore the question arises how to eliminate this negative influence on consistency without the necessity of increasing water cement ratio.

scholarly journals Highly Effective Adsorption Process of Ni(II) Ions with the Use of Sewage Sludge Fly Ash Generated by Circulating Fluidized Bed Combustion (CFBC) Technology

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3106
Author(s):  
Tomasz Kalak ◽  
Kinga Marciszewicz ◽  
Joanna Piepiórka-Stepuk
Keyword(s):  
Fly Ash ◽  
Sewage Sludge ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Fluidized Bed Combustion ◽  
Nickel Ions ◽  
Suitable Material ◽  
Circulating Fluidized Bed Combustion

Recently, more and more attention has been paid to the removal of nickel ions due to their negative effects on the environment and human health. In this research, fly ash obtained as a result of incineration of municipal sewage sludge with the use of circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Ni(II) ions in adsorption processes. The properties of the material were determined using analytical methods, such as SEM-EDS, XRD, BET, BJH, thermogravimetry, zeta potential, SEM, and FT-IR. Several factors were analyzed, such as adsorbent dose, initial pH, initial concentration, and contact time. As a result of the conducted research, the maximum sorption efficiency was obtained at the level of 99.9%. The kinetics analysis and isotherms showed that the pseudo-second order equation model and the Freundlich isotherm model best suited this process. In conclusion, sewage sludge fly ash may be a suitable material for the effective removal of nickel from wastewater and the improvement of water quality. This research is in line with current trends in the concepts of circular economy and sustainable development.

Assessment of Hydration Degree of Cement in the Fly Ash-Cement Pastes Based on the Calcium Hydroxide Content

2014 ◽  
Vol 875-877 ◽  
pp. 177-182 ◽  
Author(s):  
Xiang Li ◽  
Hua Quan Yang ◽  
Ming Xia Li
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Cement Hydration ◽  
Ash Content ◽  
Content Increase ◽  
Hydration Degree ◽  
Equilibrium Calculation ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio

The hydration degree of fly ash and the calcium hydroxide (CH) content were measured. Combined with the equilibrium calculation of cement hydration, a new method for assessment of the hydration degree of cement in the fly ash-cement (FC) pastes based on the CH content was developed. The results reveal that as the fly ash content increase, the hydration degree of fly ash and the CH content decrease gradually; at the same time, the hydration degree of cement increase. The hydration degree of cement in the FC pastes containing a high content of fly ash (more than 35%) at 360 days is as high as 80%, even some of which hydrates nearly completely. The effect of water-cement ratio to the hydration degree of cement in the FC pastes is far less distinct than that of the content of fly ash.

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%.

scholarly journals Partial Replacement of Portland-Composite Cement by Fluidized Bed Combustion Fly Ash

2017 ◽  
Vol 29 (8) ◽  
pp. 04017061 ◽  
Author(s):  
Jouni Rissanen ◽  
Katja Ohenoja ◽  
Paivo Kinnunen ◽  
Mirja Illikainen
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Partial Replacement ◽  
Fluidized Bed Combustion ◽  
Composite Cement

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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