Binder chemistry of sodium carbonate-activated CFBC fly ash

2018 ◽  
Vol 51 (3) ◽  
Author(s):  
S. M. Park ◽  
J. H. Seo ◽  
H. K. Lee
2014 ◽  
Vol 629-630 ◽  
pp. 306-313 ◽  
Author(s):  
Mao Chieh Chi ◽  
Ran Huang ◽  
Te Hsien Wu ◽  
Toun Chun Fou

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%.


2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744087 ◽  
Author(s):  
Guozhong Dai ◽  
Weicheng Shi ◽  
Xiaoshu Jiang ◽  
Guicai Shi ◽  
Yaxing Zhang

In order to develop a kind of slurry with low permeability which has some adsorption and retardation to the pollutants in leachate to be used in antiseepage engineering of leachate for landfill site, experiments based on orthogonal method were performed. The optimal PBFC slurry was selected: bentonite 18–26%, cement 16–24%, fly ash 18–20%, TOJ800-10 water reducing agent 0.01–0.03%, polyvinyl alcohol 0.2–0.8%, sodium carbonate 0.8–1.5% and water 680–780/1000 mL seriflus. The material has good groutability and a concretion stone ratio which is greater than 99.6%. The coefficient of permeability of 28-day concretion body is 0.53 × 10[Formula: see text]–1.86 × 10[Formula: see text] cm/s and the compressive strength is 0.64–1.04 MPa. The slurry has good adsorption and retardation properties. The block rate of NH4-N and phosphorus reached 98.28%, and the block rate of CODCr and BOD5 reached 85.67%. The block rate of Hg, Pb and other heavy metal ions reached 99.8%. The PBFC slurry improved the retardation capability of the pollutants of the leachate at the landfill site by its infiltration sedimentation and adsorption fixation.


2016 ◽  
Vol 722 ◽  
pp. 132-139 ◽  
Author(s):  
Tomáš Váchal ◽  
Rostislav Šulc ◽  
Tereza Janků ◽  
Pavel Svoboda

This paper describes chemical properties of fly ash from Circulating fluidized Bed Combustion (CFBC). There are shown thermal properties of fly ash using calorimetric measurement and the total content of calcium oxide CaO was determined. This paper describes the methods of measurement for determining these properties including granulometric measurement and chemical analysis. Also there were described and evaluated properties of fly ash and the reactivity of the fly ash was compared.


2012 ◽  
Vol 509 ◽  
pp. 181-188 ◽  
Author(s):  
De Yu Chen ◽  
Yun Yan ◽  
Yuan Zheng Liu ◽  
Meng Huang

The comprehensive performance, such as water demand, hydration heat, expansion, and self-hardening of circulation fluidized bed combustion (CFBC) fly ash ground by the laboratory mill were studied in this paper. Results show that the percentage of fine particles and fluidity of CFBC fly ash increased with grinding time. However, the water demand at normal consistency of the CFBC ash decreased with grinding time. The hydration exothermic rate of the paste has been accelerated and the time of reaching the volume stability has been shortened. Meanwhile, the compressive strength of the paste and the content of ettringite in the matrix increased with the curing time in the early age, but reversed later.


2011 ◽  
Vol 32 (4) ◽  
pp. 255-266 ◽  
Author(s):  
Rafał Kobyłecki

Unburned carbon in the circulating fluidised bed boiler fly ash The paper describes the results of various actions and industrial tests conducted in order to decrease the content of unburned carbon in the fly ash of a circulating fluidised bed combustor (CFBC). Several attempts to improve the situation were made and the effects of several parameters on the unburned carbon content in the fly ash were investigated (e.g. bed temperature, cyclone separation efficiency, fuel particle size distribution, boiler hydrodynamics, grid design, and fuel data). Unfortunately, no satisfactory solution to these problems was found. Probably, apart from attrition and char fragmentation, additional factors also contributed to the formation of unburned carbon in the CFBC fly ash.


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