Cementitious properties and hydration mechanism of circulating fluidized bed combustion (CFBC) desulfurization ashes

Li, Xiangguo; Quan-bin, Chen; Huang, Kuai-zhong; Ma, Baoguo; Wu, Bei

doi:10.1016/j.conbuildmat.2012.05.017

Cited by 104 publications

(67 citation statements)

References 18 publications

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“…Sheng et al [1] investigation of the cementitious properties of fly ash produced by CFBC boilers cofiring coal and high-sulfur petroleum coke revealed that a high f-CaO content and a high SO 3 content enhance cementitious properties; in other words, CFB fly ash is cementitious. Li et al revealed that CFB fly ash has high pozzolanic reactivity and can be used as a cement admixture [7]. Chi et al indicated that CFB fly ash can increase water absorption and effectively reduce initial surface absorption [3].…”

Section: Introductionmentioning

confidence: 99%

Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

Lin¹,

Cheng²,

Ho³

et al. 2017

TOCIEJ

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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, SO 3 , and SiO 2 in concentrations of 37.8%, 9.2%, and 2.2%, respectively. The crystals of CFB fly ash contained 3CaO.SiO 2 , 2CaO.SiO 2 , 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 C 3 S and C 2 S were consumed to form C-S-H gel, resulting in an increase in the Q 1 and Q 2 groups identified by 29 Si Nuclear Magnetic Resonance (NMR) spectroscopy. Furthermore, the peak of the Q group decreased, but those of the Q 1 and Q 2 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.

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Section: Introductionmentioning

confidence: 99%

Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

Lin¹,

Cheng²,

Ho³

et al. 2017

TOCIEJ

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“…In addition, the lime improves the alkalinity of the system and activates the activity of desulfurization ash, leading to the corrosion of the densified outer layer of desulfurization ash particles and leaving more active cores exposed for reacting forming additional hydration products [6,7]. It also accelerates the generation of AFt, CASAH and gypsum, therefore it promotes the development of early strength [8].…”

Section: Influence Of Alkali Excitation Agent On Desulfurization Ash mentioning

confidence: 98%

Effect of activators, admixtures and temperature on the early hydration performance of desulfurization ash

Wang

Ke-feng

et al. 2014

Construction and Building Materials

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“…The utilization of the ash is urgent for its annual discharge of about 20 million tons in China. With rich content of active SiO 2 and Al 2 O 3 , it has high pozzolanic activity [1][2][3][4] , making it a potential supplementary cementitious material for concrete production.…”

Section: Introductionmentioning

confidence: 99%

Adsorption mechanism of polycarboxylate-based superplasticizer in CFBC ash-Portland cement paste

Song

Guo

Qian

et al. 2014

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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Circulating fl uidized bed combustion (CFBC) ash exhibits the desirable pozzolanic activity which makes it a potential supplementary cementitious material to replace cement for concrete production. However, the high unburnt carbon content and porous surface structure of CFBC ash may adsorb water reducer and thereby signifi cantly reduce the effi ciency of water-reducing agents. The adsorption mechanism of polycarboxylate superplasticizer in CFBC ash-Portland cement paste was investigated by ultraviolet-visible spectrophotometer, and the conception of "invalid adsorption site" of CFBC ash was presented. The results show that the adsorption behavior of polycarboxylate superplasticizer in coal ash-Portland cement paste can be described by Langmuir isothermal adsorption equation. The adsorption capacity of CFBC ash-Portland cement paste is higher than that of pulverized coal combustion (PCC) fl y ash-Portland cement paste. Moreover, the adsorption amount of polycarboxylate superplasticizer increases with the ratio of ash-to-cement in the paste. At last, the fl uidity of CFBC ash-Portland cement paste is lower than that of the PCC fl y ash paste. This work suggests that when CFBC ash is used as concrete admixture, the poor fl owability of the cementitious system due to the high adsorption of water and water-reducing agent should be taken into consideration. SONG Yuanming (宋远明): Assoc. Prof.; Ph D;

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Cementitious properties and hydration mechanism of circulating fluidized bed combustion (CFBC) desulfurization ashes

Cited by 104 publications

References 18 publications

Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

Effect of activators, admixtures and temperature on the early hydration performance of desulfurization ash

Adsorption mechanism of polycarboxylate-based superplasticizer in CFBC ash-Portland cement paste

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