Influence of mechanical grinding on pozzolanic characteristics of circulating fluidized bed fly ash (CFA) and resulting consequences on hydration and hardening properties of blended cement

2018 ◽  
Vol 132 (3) ◽  
pp. 1459-1470 ◽  
Author(s):  
Jihui Zhao ◽  
Duanle Li ◽  
Shucong Liao ◽  
Dongmin Wang ◽  
Hao Wang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Blended Cement ◽  
Mechanical Grinding

scholarly journals Elucidating the Pozzolanic Characteristics of Pastes Containing Circulating Fluidized Bed Fly Ash

2015 ◽  
Vol 9 (1) ◽  
pp. 180-186
Author(s):  
Kae-Long Lin ◽  
Chao-Lung Hwang ◽  
Yu-Min Chang
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Fluidized Bed ◽  
Ordinary Portland Cement ◽  
Circulating Fluidized Bed ◽  
Setting Time ◽  
Blended Cement ◽  
Curing Time ◽  
Cement Pastes ◽  
Space Ratio

The aim of this study is to investigate the pozzolanic characteristics of circulating fluidized bed fly ash blended cement (CFBFABC) paste containing circulating fluidized bed fly ash (CFBFA). The initial and final setting time of CFBFABC pastes with CFBFA retards with an increasing CFBFA content. CFBFABC pastes containing 10% CFBFA exhibited a compressive strength similar to that of ordinary Portland cement pastes at the ages of 90 days. X-ray diffraction peaks indicated the presence of portlandite, ettringite, and unreacted C3S (32.6°) and C2 (41.9°). The gel/space ratio of the CFBFABC pastes increased with the curing time and decreased as the CFBFA content increased. The gel/space ratio increased with the curing time because of the progress of hydration, which led to some of the pores being filled. At the ages of 90 days, the gel/space ratio of the CFBFABC pastes containing 10% CFBFA increased to approximately 14%, it is possibly the consumption of Ca(OH)2 and the formation of C-S-H in the CFBFABC pastes. The CFBFABC pastes containing 10% CFBFA did not exhibit any major decrease in the gel/space ratio. It exhibited favorable mechanical characteristics that were observed when the mixing ratio of CFBFA was 10%. Furthermore, CFBFA has the potential, as a pozzolanic material, partially to replace ordinary Portland cement.

scholarly journals Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

2017 ◽  
Vol 11 (1) ◽  
pp. 176-186 ◽  
Author(s):  
Kae- Long Lin ◽  
Ta-Wui Cheng ◽  
Chih-Hsuan Ho ◽  
Yu-Min Chang ◽  
Kang-Wei Lo
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Petroleum Coke ◽  
Circulating Fluidized Bed ◽  
Blended Cement ◽  
Curing Time ◽  
Cement Pastes ◽  
Cfb Boiler ◽  
Pozzolanic Material ◽  
High Sulfur Content

A circulating fluidized bed (CFB) boiler generates energy by burning petroleum coke. Because burnt petroleum coke has a high sulfur content, limestone is added to the boiler to reduce the emittance of sulfur dioxide through desulfuration. The residue collected from the boiler is called CFB ash. CFB boilers in Taiwan can produce 328,000 tonnes of CFB fly ash per year. In this study, the pozzolanic characteristics of CFB fly ash were investigated by blending CFB fly ash and ordinary Portland cement (OPC). The CFB fly ash was mainly composed of CaO, SO3, and SiO2 in concentrations of 37.8%, 9.2%, and 2.2%, respectively. The crystals of CFB fly ash contained 3CaO.SiO2, 2CaO.SiO2, Ca(OH)2, C-S-H (Tobermolite), and Ettringite. The results revealed that applying the toxicity characteristic leaching procedure to CFB fly ash renders it suitable for use in blended cement. At later curing ages (90 days), the pore volumes of both the OPC and the CFB-fly-ash-blended cement pastes (CFBFABCP) decreased as the curing time increased. A possible explanation is that C3S and C2S were consumed to form C-S-H gel, resulting in an increase in the Q1 and Q2 groups identified by 29Si Nuclear Magnetic Resonance (NMR) spectroscopy. Furthermore, the peak of the Q0 group decreased, but those of the Q1 and Q2 peaks increased with an increasing curing time. The pozzolanic activity of the CFBFABCP containing 10% CFB fly ash indicates that it is a suitable substitute for OPC in blended cement.

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.

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%.

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