Elastic properties of high alumina cement castables from room temperature to 1600°C

Nonnet, Emmanuel; Lequeux, Nicolas; Boch, P.

doi:10.1016/s0955-2219(98)00255-6

Cited by 111 publications

(58 citation statements)

References 16 publications

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“…By using MS, the ion currents of different gases are recorded, providing gas information during the heating. In the TGA curve of noncarbonated sample, the weight loss in the range of 40-400°C is normally related to the dehydration of C-S-H (Noumowé 1995, Richard 1999, part of the carboaluminate hydrates (Nonnet, Lequeux et al 1999), AFm and AFt (Zhou and Glasser 2001) phases, as well as to the emission of physically-bound water (Noumowé 1995). This is confirmed by the mass spectrum of H 2 O (see Figure 4a).…”

Section: Profiles Of the Portlandite And The Amounts Of Cacomentioning

confidence: 99%

Development of porosity of cement paste blended with supplementary cementitious materials after carbonation

2017

Construction and Building Materials

147

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Supplementary cementitious materials (SCMs) like fly ash (FA) and blast furnace slag (BFS) are normally used to replace parts of Ordinary Portland cement (OPC) to reduce the cost and CO 2 emission. Some consequences are the reduction of portlandite (CH) content and the formation of C-S-H with low Ca/Si ratio, due to pozzolanic reactions. It is known that carbonation of portlandite leads to a reduction in the porosity which is ascribed to the positive difference of molar volumes between CH and CaCO 3 . However, the influence on the porosity caused by the carbonation of C-S-H is still controversial. The molar volume change due to the carbonation of C-S-H depends on the properties of C-S-H (like Ca/Si ratio, water content) and the water remained in silica gel. Moreover, the decalcification of C-S-H with the Ca/Si ratio lower than 1.2 can cause more structure changes and shrinkage of C-S-H. During the carbonation of cement paste blended with SCMs, less portlandite but a relatively high amount of C-S-H with low Ca/Si ratio will be carbonated. The pore structure will evolve in a different way, comparing with Portland cement paste. Therefore, it's very important to figure out the pore structure development of cement paste blended with SCMs under carbonation.In this paper, the binary cement pastes (B70, blended with blast furnace slag, and F30, blended with fly ash) and ternary cement pastes (F10B54 and F30B30, blended with blast furnace slag and fly ash) are studied and compared with Portland cement paste. Mercury Intrusion Porosimetry (MIP) and nitrogen adsorption isotherm are used to determine the pore volume and size distribution of capillary pores and gel pores (2-37 nm), respectively. Thermogravimetric analysis (TGA) is used to determine the amounts of portlandite and CaCO 3 . The results show that the amount profiles of portlandite and CaCO 3 can be used as a more accurate method to study the carbonation in blended cement paste, comparing with the phenolphthalein test. Carbonation of most of the species of C-S-H results in the increase of the porosity of cement paste. CaCO 3 contributed by the carbonation of low Ca C-S-H is dominant in blended cement paste B70, F10B54 and F30B30. Both the total and effective capillary porosity increases in the above-mentioned paste after the carbonation. Moreover, total porosities of B70 and F10B54 increase with the increasing amount of C-S-H involving in carbonation. However, the increment of the total porosity of F30B30 decreases with the increasing amount of C-S-H being carbonated. Carbonation of C-S-H increases the volume and size of the small gel pore, and creates more capillary pores. This peculiar phenomenon is more evident for the mixture with a higher proportion of SCMs, like B70 and F30B30. The results reveal that the carbonation of C-S-H formed in pozzolanic reactions cause the increase of the total and capillary porosity in cement paste blended with SCMs, which will bring adverse effects on the durability of blended cement concrete exposed to the carbonation...

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Section: Profiles Of the Portlandite And The Amounts Of Cacomentioning

confidence: 99%

Development of porosity of cement paste blended with supplementary cementitious materials after carbonation

2017

Construction and Building Materials

147

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“…The ultrasonic spectrometer used to measure the shear and compression modulus is similar to previously described devices operating in the reflection mode [17,18]. Basically, the systems follows the temporal evolution of a broad band pulse (1 MHz) generated by an emitter/receiver transducer, traveling through a Plexiglas delay line and reflected at the Plexiglas/paste interface.…”

Section: Ultrasonic Measurementsmentioning

confidence: 99%

Gelation, Shear-Thinning and Shear-Thickening in Cement Slurries

Lootens

Hébraud

Lécolier

et al. 2004

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Coagulation, rhéofluidification et rhéoépaississement dans les coulis de ciment -Le comportement rhéologique des coulis de ciment peut se décliner en plusieurs comportements élémentaires : -la formation rapide d'un gel faible au repos ; -l'effondrement de ce gel sous une contrainte critique directement liée à l'intensité des forces interparticulaires ; -la destruction progressive des fragments de ce gel sous cisaillement modéré, avec un comportement d'autant plus rhéofluidifiant que la taille des grains élémentaires est faible ; -la reformation, d'abord transitoire puis continue, à fort gradient de vitesse, de structures résistant au cisaillement, probablement sous forme de chaînes de grains au contact avec, sur le plan rhéologique, l'apparition d'un rhéoépaississement ; -éventuellement, le blocage de l'écoulement. Nous démontrons les mécanismes de passage d'un état au suivant. Nous montrons comment l'addition d'agents dispersants favorise l'état rhéoépaississant au détriment de l'état rhéofluidifiant et comment le contrôle de l'état de surface des grains et du frottement intergranulaire permet de limiter le rhéoépaississement et les risques de blocage. Abstract -Gelation, Shear-Thinning and Shear-Thickening in Cement Slurries

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“…The ultrasonic parameters cannot directly correlate with ionic radius of the rare earth element; rather it depends on the structural compactness of sample which is influenced by various factors like preparation method 28 , sintering temperature 29 and particle size 30 . However, attempts have been made to reveal the ultrasonic behaviour of rare earth element [31][32] and found that a decrease in ultrasonic velocities with an increase in ionic radii.…”

Section: Resultsmentioning

confidence: 99%

Effect of rare earth ions on transition temperature in perovskite materials by on-line ultrasonic studies

Sankarrajan¹,

Sakthipandi²,

Rajendran³

2012

Mat. Res.

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On-line measurements of ultrasonic longitudinal velocity, shear velocity and longitudinal attenuation were carried out on R 1-x Sr x MnO 3 perovskites (R = La, Pr, Nd and Sm) for different compositions of Sr, at a fundamental frequency of 5 MHz over wide range of temperatures using the through-transmission method. The observed maxima/minima in velocities and attenuation have been discussed with decrease in ionic radii and composition. As a decrease in the ionic radii of rare earth elements leads to a decrease in transition temperature (T c ), the results that are observed show that measurement is one of the best tools to explore the structural/phase transition on-line velocity in perovskite manganese materials as a function of the ionic radii of rare earth elements.

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Elastic properties of high alumina cement castables from room temperature to 1600°C

Cited by 111 publications

References 16 publications

Development of porosity of cement paste blended with supplementary cementitious materials after carbonation

Development of porosity of cement paste blended with supplementary cementitious materials after carbonation

Gelation, Shear-Thinning and Shear-Thickening in Cement Slurries

Effect of rare earth ions on transition temperature in perovskite materials by on-line ultrasonic studies

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