Phase transformation on heating of an aged cement paste

Stepkowska, E. T.; Blanes, José María Martínez; Franco, Francisco; Real, C.; Pérez-Rodríguez, J. L.

doi:10.1016/j.tca.2003.11.057

Cited by 88 publications

(44 citation statements)

References 13 publications

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“…This wide temperature range of effect may indicate a different degree of crystallinity of the carbonate minerals [31] or the thermal decomposition of cementitious phases, e.g. jennite [44]. The normal singlestep reaction of calcite thermal decomposition is gradually turned into a double-stage reaction by strong weathering conditions, whereas the calcite structure is disintegrated by the weathering process [45].…”

Section: Resultsmentioning

confidence: 99%

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

et al. 2015

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The aim of this study was to investigate the thermal behaviour of cement-asbestos wastes and to determine whether it is possible to use them in the production of building ceramics, e.g. clinker bricks. In the first part of the research, the process of cement-asbestos thermal decomposition was studied. This asbestos material contained the chrysotile and crocidolite variety of asbestos. The results of this study allowed to determine the lowest temperature of thermal treatment that provides asbestos detoxification. The second part of the paper presents the results of a preliminary study on using previously calcined cement-asbestos wastes as an additive to ceramic masses typical for clinker bricks. Green compacts containing various amounts of cement-asbestos wastes were sintered and then ceramic properties were determined. The results of the study indicate that calcined asbestos-containing materials can be used as one of the secondary raw materials in the production of clinker ceramics.

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Section: Resultsmentioning

confidence: 99%

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

et al. 2015

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“…• C. As already illustrated in the literature [64,65,46,66,47], the decomposition of CC is characterized by the presence of three DTG/MS peaks (see Figs The principle of TGA quantification of CH and CC consists in tracing DTG and MS diagrams related to H 2 O and CO 2 , respectively, finding the beginning and the end of each peak, and measuring the corresponding weight loss which represents a percentage of the mass of the freezedried samples. The tangential method is generally used for TGA assessment of CH in order to take into account the C-S-H dehydration in the same temperature range as CH decomposition [85].…”

Section: Thermogravimetric Analysis (Tga)mentioning

confidence: 96%

“…Many authors have pointed out the presence of amorphous CC by comparing TGA and XRD data [12,74,10]. Stepkowska et al [64,75] have described the presence of complex compounds of amorphous forms of carbonate hydroxide hydrates (crypto-nano-cristalline forms) whose decomposition happens in such low temperature range. Brecevic [11] indicates that the formation of amorphous CC compounds occurs if the pH value of the pore solution is low (below 9) which is certainly the case for our materials when the carbonation level becomes high and for a high CO 2 concentration.…”

Section: Tga-dtg-ms and Xrd Characterizationmentioning

confidence: 99%

Investigation of the carbonation mechanism of CH and C-S-H in terms of kinetics, microstructure changes and moisture properties

Morandeau

Thiéry

Dangla

2014

Cement and Concrete Research

760

285

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The purpose of this article is to investigate the carbonation mechanism of CH and C-S-H within type-I cement-based materials in terms of kinetics, microstructure changes and water released from hydrates during carbonation. Carbonation tests were performed under accelerated conditions (10% CO 2 , 25• C and 65± 5% RH). Carbonation profiles were assessed by destructive and non-destructive methods such as phenolphthalein spray test, thermogravimetric analysis, and mercury intrusion porosimetry (destructive), as well as gamma-ray attenuation (non-destructive). Carbonation penetration was carried out at different ages from 1 to 16 weeks of CO 2 exposure on cement pastes of 0.45 and 0.6 w/c, as well as on mortar specimens (w/c = 0.50 and s/c = 2). Combining experimental results allowed us to improve the understanding of C-S-H and CH carbonation mechanism. The variation of molar volume of C-S-H during carbonation was identified and a quantification of the amount of water released during CH and C-S-H carbonation was performed.

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“…A wide temperature range of CO 2 release may indicate a different degree of crystallinity of the calcite or the presence of other carbonate minerals in the tested samples [33]. The weak effect from H 2 O at 600°C on the EGA curve may come from the thermal decomposition of chrysotile asbestos and/or more complicated CSH phase components [41,43].…”

Section: Resultsmentioning

confidence: 99%

Thermal decomposition of asbestos-containing materials

Kusiorowski

Zaremba

Piotrowski

et al. 2013

J Therm Anal Calorim

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Asbestos is the common name applied to a group of natural, fibrous silicate minerals, which were once one of the most popular raw materials to be used in building materials. Asbestos was mainly used for the production of assortment asbestos-cement products. Today it is generally known that asbestos belongs to the group of hazardous materials and shows carcinogenic activity. In Poland, asbestos-containing materials are stored in special landfills. This is not the final solution to the asbestos problem because the fibrous structure of asbestos is still maintained. Therefore, methods based on recycling must be found which will be able to destroy asbestos' dangerous fibrous structure. One of these methods may be thermal decomposition, where chemically combined water is released from the asbestos materials during heating. This leads to changes in the crystal structure and to the formation of new mineral phases. The aim of the preliminary research presented in this study was to determine the thermal behaviour as well as the structural and phase transformations of asbestos-cement materials during heating to high temperature. In the present study, three different types of asbestos-containing materials from Poland were examined. Differential thermal analysis, thermogravimetry with evolved gas analysis, X-ray diffraction, infrared spectroscopy and scanning electron microscopy were used to study the thermal decomposition of asbestos-cement samples. It was found that there were no significant differences between the type of asbestos-cement samples used-their thermal decomposition takes place in a similar way.

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Phase transformation on heating of an aged cement paste

Cited by 88 publications

References 13 publications

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

Investigation of the carbonation mechanism of CH and C-S-H in terms of kinetics, microstructure changes and moisture properties

Thermal decomposition of asbestos-containing materials

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