Effects of aphthitalite on the formation of clinker minerals and hydration properties

Huang, Liming; Song, Wenjuan; Li, Haoxin; Zhang, Hui; Yang, Zhenghong

doi:10.1016/j.conbuildmat.2018.06.082

Cited by 13 publications

(5 citation statements)

References 33 publications

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“…The elemental compositions of the circular particles (spot 4) were close to those of the uncarbonated sample at the same temperature (spot 2), with Ca/Si at 2.52. Considering that the formation temperature of the C 3 S was much higher than 950 °C [ 42 ], the main compositions at 950 °C should be the mixtures of crystalline C 2 S and lime. In general, the SEM results were in line with the MIP results.…”

Section: Resultsmentioning

confidence: 99%

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Luo

et al. 2022

Materials

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The microstructural evolutions of both uncarbonated and carbonated cement pastes subjected to various high temperatures (30 °C, 200 °C, 400 °C, 500 °C, 600 °C, 720 °C, and 950 °C) are presented in this study by the means of mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It was found that the thermal stabilities of uncarbonated cement pastes were significantly changed from 400 to 500 °C due to the decomposition of portlandite at this temperature range. More large pores and microcracks were generated from 600 to 720 °C, with the depolymerization of C-S-H. After carbonation, the microstructures of carbonated cement pastes remained unchanged below 500 °C and started to degrade at 600 °C, due to the decompositions of calcium carbonates and calcium modified silica gel. At 950 °C, both uncarbonated and carbonated cement pastes showed a loosely honeycombed microstructure, composed mainly of β-C2S and lime. It can be concluded that carbonation improves the high-temperature resistance of cement pastes up to 500 °C, but this advantage is lost at temperatures over 600 °C.

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Section: Resultsmentioning

confidence: 99%

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Luo

et al. 2022

Materials

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“…18 Thenardite being an anhydrous and hygroscopic mineral, the peak is more likely to be attributed to others quoted minerals. Aphthitalite is either added to the clinker, 94 or generated depending on the sulfur content in the coke fuel used during clinker manufacturing. 95 It can also be attributed to aphthitalite efflorescence occurring on the surface between the glass vial containing the Raman probe and the cement, although this is quoted to only occur in superplasticized concretes.…”

Section: Resultsmentioning

confidence: 99%

Benefits of Chemometric and Raman Spectroscopy Applied to the Kinetics of Setting and Early Age Hydration of Cement Paste

Mechling

Janvier-Badosa

et al. 2022

Appl Spectrosc

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The addition of water is used to past by internal post-curing of hardening cement. Hydration and curing of cementitious are widely identified by non-destructive 1H Nuclear Magnetic Resonance (NMR) measurements of transverse relaxation time and self-diffusion. However, those non-destructive analytical methodologies do not give a truly chemical characterization of the cement matrix during the hydration and curing process. Indeed, the NMR studies only the water dynamics of hydrating cement with internal post-curing. Recent researches indicated chemometrics coupled to the Raman spectroscopy allowed to reaching a better understanding of chemical processes. Recent advances in computing gave industries and research centers the opportunity to generate cost effective data. In this work, an original method is presented, which uses both a data analysis and a non-invasive, non-destructive Raman monitoring of the hydration reaction of a Portland cement. Data was then analyzed by means of chemometrics methods (principal components analysis (PCA), independent components analysis (ICA), and multivariate curve resolution-alternated least-squares (MCR-ALS) with SIMPLISMA and OPA initialization). Results were compared to the ones obtained with thermogravimetric analysis of this cement paste. Besides the consistency of results from both analytical measurements, chemometrics coupled to Raman spectroscopy accurately revealed the details of the setting without any samples collection. The acquisition frequency allowed a proper identification of the occurrence of each of the various phases involved in the hydration and setting process.

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“…It is highlighted that mainly for the F1 formulation, in the case of the belite phase, potassium (K) contents are identified in a proportion greater than 0.75%; at this content negative effects on the alite phase formation are observed according to Kolovos et al (28). This is due to the increase in the viscosity of the liquid phase, which negatively affects the reaction of belite (C 2 S) with CaO to form alite (C 3 S) (35). Similarly, sulfur (S) contents are greater than 0.5% in the belite phase, what causes an effect of stabilization in the belite phase, preventing conversion to alite phase (36).…”

Section: Microscopic Analysismentioning

confidence: 98%

Use of industrial wastes for the synthesis of belite clinker

2020

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The synthesis of belite clinker was studied using industrial wastes: paper sludge, cement kiln dust and rice husk ashes, as substitutes for natural raw materials. Wastes were characterized by XRF, XRD and TG analysis. Different formulations were prepared to produce clinker at 1300, 1350 and 1400 °C. The clinker obtained was characterized using optical microscopy, XRD and f-CaO content determined by ethylene glycol method. Finally, the hydration of prepared cements with the clinkers was evaluated by isothermal microcalorimetry. It was found that by mixing paper sludge, cement kiln dust and rice husk ashes, it is possible to obtain belite clinker with f-CaO content below 0.5%, in clinkering temperatures between 1350 °C and 1400 °C without the use of natural raw materials. It was found that these cements have a high hydration kinetic, far above the rate of Ordinary Portland Cement, due mainly by the amorphous phase content in clinkers obtained.

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Effects of aphthitalite on the formation of clinker minerals and hydration properties

Cited by 13 publications

References 33 publications

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Benefits of Chemometric and Raman Spectroscopy Applied to the Kinetics of Setting and Early Age Hydration of Cement Paste

Use of industrial wastes for the synthesis of belite clinker

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