Alkalies in cement: A review I. Forms of Alkalies and their effect on clinker formation

Jawed, I.; Skalny, Jan

doi:10.1016/0008-8846(77)90056-4

Cited by 85 publications

(48 citation statements)

References 13 publications

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“…The alkali cation (mainly Na + and/or K + ) incorporated into hardened cement pastes and concrete can from either the composition of clinker (e.g., alkali sulfates) (Jawed and Skalny 1977), supplementary cementitious materials (SCMs) (Duchesne and Berube 1994), and aggregates , or exposed alkalibearing environments (e.g. deicing salts or seawater), or mixing solution (e.g.…”

Section: Introductionmentioning

confidence: 99%

Effect of Alkalis on Cementitious Materials:Understanding the Relationship between Composition, Structure, and Volume Change Mechanism

Radlińska

2017

ACT

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Journal of Advanced AbstractPrevious studies demonstrated that alkalis can considerably affect the volumetric properties of hardened cementitious binders, including shrinkage, creep, and micro-cracking. The objective of this paper is to reexamine the effect of alkalis on the composition, nanostructure, phase stability, and morphology of calcium-silicate-hydrate (C-S-H) in cementitious materials, and to further propose a conceptual model bridging the C-S-H characters with its volume change mechanisms in alkali-enriched systems. The proposed microstructural model is an extension of the colloidal model of C-S-H considering the effect of alkalis. It is suggested that the presence of alkalis makes C-S-H more thermodynamically unstable and structurally disrupted, and easier to reorganize and redistribute upon drying-induced internal stresses or external loading. In addition, new experimental results regarding the influence of lithium on shrinkage and micro-cracking of alkali-activated blast-furnace slag are discussed. It shows that lithium addition can dramatically improve the cracking resistance and volumetric stability of alkali-activated slag.

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Section: Introductionmentioning

confidence: 99%

Effect of Alkalis on Cementitious Materials:Understanding the Relationship between Composition, Structure, and Volume Change Mechanism

Radlińska

2017

ACT

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“…% 138,139 . More than half of the S originating from raw materials and fuel appears in the clinker; the rest is lost in the flue gas and in the kiln dust 97 .…”

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confidence: 99%

“…The loss on ignition (LOI) is equivalent to the loss in mass that it will undergo in a kiln (free of H 2 O and CO 2 from carbonates) and indicates how complete the calcination processing is. From practical experience, α has the value of 0.5 because there is substantial excess of K 2 O over Na 2 O 124 and analyses of different clinker compositions have revealed that nearly the entire amount of K and half the amount of Na form sulfate 97,125 .…”

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confidence: 99%

Review: Circulation of Inorganic Elements in Combustion of Alternative Fuels in Cement Plants

et al. 2015

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Cement production is an energy-intensive process, which traditionally has been dependent on fossil fuels. However, the use of alternative fuels, i.e., selected waste, biomass and by-products with recoverable calorific value, is constantly increasing. Combustion of these fuels is more challenging compared to fossil fuels, due to lack of experience and different chemical and physical properties. When complete oxidation of fuels in the calciner and main burner is not achieved, they burn in direct contact with the bed material of the rotary kiln, causing local reducing conditions and increasing the internal circulation of S, Cl, Na, and K. Compounds containing these elements, such as alkali salts, evaporate when exposed to high temperatures and subsequently condense in colder parts of the plant. The transformation of the volatile inorganic species at different locations in the cement plant is important, because a high internal circulation affects the process stability and operation through formation of build-ups and blockages, ring formation, and shell corrosion, resulting in reduced clinker production, higher heat consumption, and kiln or plant stops. The present review describes the internal cycles of inorganic elements that are established within the cement plant and their dependence on process parameters. Special focus is given to the sulfur cycle. This cycle is intensified by CaSO 4 decomposition, making it sensitive to local reducing conditions.

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“…They majorly affect the determination of the burning zone and the clinker compound formation, they can also facilitate and quick the clinkerization process, by decreasing the liquid phase temperature and mineral fusible eutectic in the aim of saving the clinker production energy and improving the cement compound reactivity [2,3]. They can also improve the hydraulic properties of clinker [3,[6][7][8][9][10][11][12][13] The aim of this work was to examine the impact of calcium fluoride mineralizer (CaF 2 ) on the decreasing temperature of burning of Moroccan industrial raw mixtures, and to study it effect on chemical, mineralogical, and mechanical properties of the clinker cement. This mineralizer is added separately to five categories of industrial raw mixtures of Moroccan cement factory.…”

Section: Introductionmentioning

confidence: 99%

Influence of Fluorine on Clinker burnability and mechanical properties of CPA Moroccan cement

et al. 2018

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Abstract. It has been found that the addition of certain components, despite their low concentration in raw mix, may accelerate and enhance the reactivity of the cement raw mix. The utilization of mineralizers to facilitate and quicken the process of clinkerization backpedals numerous years, the concept of using such mineralizers to burn normal raw mixes at a much lower temperature with the end goal of decreasing the fuel necessities of the furnace and to enhance the cement proprieties has become to be seriously considered over the most recent couple of years. The subject of this paper is to investigate the impact of calcium fluoride as mineralizer on addition during the clinkerization process of industrial raw mixtures and its effect on chemical, mineralogical, and mechanical properties of CPA Moroccan cement. Five different raw meals were utilized and were burned with 2% of calcium fluoride. The resulting clinker was analyzed by X-ray diffraction (XRD) and fluorescence spectroscopy to determine the chemical phases of the obtained clinker, and the mechanical properties of resulting CPA cement were determined. The results show that the addition of 2% of CaF 2 to the clinker raw meal induced a decrease in the burning temperature and free lime, while improving the clinker phase formation and the mechanical properties of obtained cement.

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Alkalies in cement: A review I. Forms of Alkalies and their effect on clinker formation

Cited by 85 publications

References 13 publications

Effect of Alkalis on Cementitious Materials:Understanding the Relationship between Composition, Structure, and Volume Change Mechanism

Effect of Alkalis on Cementitious Materials:Understanding the Relationship between Composition, Structure, and Volume Change Mechanism

Review: Circulation of Inorganic Elements in Combustion of Alternative Fuels in Cement Plants

Influence of Fluorine on Clinker burnability and mechanical properties of CPA Moroccan cement

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