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691 : Matériaux de construction. Pièces et parties composantes
Ouvrages de la bibliothèque en indexation 691
Affiner la rechercheExperimental investigation of the effect of temperature on the first desorption isotherm of concrete / Stéphane Poyet in Cement and concrete research, Vol. 39 N° 11 (Novembre 2009)
[article]
in Cement and concrete research > Vol. 39 N° 11 (Novembre 2009) . - pp. 1052–1059
Titre : Experimental investigation of the effect of temperature on the first desorption isotherm of concrete Type de document : texte imprimé Auteurs : Stéphane Poyet, Auteur Année de publication : 2010 Article en page(s) : pp. 1052–1059 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Temperature; Surface area; Adsorption; Durability; Concrete; Radioactive waste; Waste management Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : In the framework of the radioactive waste management in France, interim storage concrete structures should be submitted to temperatures up to 80 °C and subsequent desiccation. The impact of temperature on the sorption properties of concretes has been poorly studied and results are scarce. An experimental campaign was thus carried out to characterize the first desorption isotherms of a modern concrete at 30 °C and 80 °C. The results show a significant influence of the temperature increase that will have to be accounted for the durability assessment of the long-term interim storage concrete structures. Investigating the causes of these modifications, it appeared that desorption induced by temperature might be the principal mechanism rather than microstructure alteration and water properties evolution. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001495 [article] Experimental investigation of the effect of temperature on the first desorption isotherm of concrete [texte imprimé] / Stéphane Poyet, Auteur . - 2010 . - pp. 1052–1059.
Génie Civil
Langues : Anglais (eng)
in Cement and concrete research > Vol. 39 N° 11 (Novembre 2009) . - pp. 1052–1059
Mots-clés : Temperature; Surface area; Adsorption; Durability; Concrete; Radioactive waste; Waste management Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : In the framework of the radioactive waste management in France, interim storage concrete structures should be submitted to temperatures up to 80 °C and subsequent desiccation. The impact of temperature on the sorption properties of concretes has been poorly studied and results are scarce. An experimental campaign was thus carried out to characterize the first desorption isotherms of a modern concrete at 30 °C and 80 °C. The results show a significant influence of the temperature increase that will have to be accounted for the durability assessment of the long-term interim storage concrete structures. Investigating the causes of these modifications, it appeared that desorption induced by temperature might be the principal mechanism rather than microstructure alteration and water properties evolution. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001495 Flow conditions of fresh mortar and concrete in different pipes / Stefan Jacobsen in Cement and concrete research, Vol. 39 N° 11 (Novembre 2009)
[article]
in Cement and concrete research > Vol. 39 N° 11 (Novembre 2009) . - pp. 997–1006
Titre : Flow conditions of fresh mortar and concrete in different pipes Type de document : texte imprimé Auteurs : Stefan Jacobsen, Auteur ; Lars Haugan, Auteur ; Tor Arne Hammer, Auteur Année de publication : 2010 Article en page(s) : pp. 997–1006 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Fresh concrete; Workability; Rheology; Pumping Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : The variation in fresh concrete flow rate over the pipe cross section was investigated on differently coloured and highly flowable concrete mixes flowing through pipes of different materials (rubber, steel, acryl). First, uncoloured (gray) concrete was poured through the pipe and the pipe blocked. Similar but coloured (black) concrete was then poured into the pipe filled with gray concrete, flowing after the gray concrete for a while before being blocked and hardened. The advance of the colouring along the pipe wall (showing boundary flow rate) was observed on the moulded concrete surface appearing after removing the pipe from the hardened concrete. The shapes of the interfaces between uncoloured and coloured concrete (showing variation of flow rate over the pipe cross section) were observed on sawn surfaces of concrete half cylinders cut along the length axes of the concrete-filled pipe. Flow profiles over the pipe cross section were clearly seen with maximum flow rates near the centre of the pipe and low flow rate at the pipe wall (typically rubber pipe with reference concrete without silica fume and/or stabilizers). More plug-shaped profiles, with long slip layers and less variation of flow rate over the cross section, were also seen (typically in smooth acrylic pipes). Flow rate, amount of concrete sticking to the wall after flow and SEM-images of pipe surface roughness were observed, illustrating the problem of testing full scale pumping. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.bledco.com/business/Rouiba/education/Enseignement-universitaire/ECOLE [...] [article] Flow conditions of fresh mortar and concrete in different pipes [texte imprimé] / Stefan Jacobsen, Auteur ; Lars Haugan, Auteur ; Tor Arne Hammer, Auteur . - 2010 . - pp. 997–1006.
Génie Civil
Langues : Anglais (eng)
in Cement and concrete research > Vol. 39 N° 11 (Novembre 2009) . - pp. 997–1006
Mots-clés : Fresh concrete; Workability; Rheology; Pumping Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : The variation in fresh concrete flow rate over the pipe cross section was investigated on differently coloured and highly flowable concrete mixes flowing through pipes of different materials (rubber, steel, acryl). First, uncoloured (gray) concrete was poured through the pipe and the pipe blocked. Similar but coloured (black) concrete was then poured into the pipe filled with gray concrete, flowing after the gray concrete for a while before being blocked and hardened. The advance of the colouring along the pipe wall (showing boundary flow rate) was observed on the moulded concrete surface appearing after removing the pipe from the hardened concrete. The shapes of the interfaces between uncoloured and coloured concrete (showing variation of flow rate over the pipe cross section) were observed on sawn surfaces of concrete half cylinders cut along the length axes of the concrete-filled pipe. Flow profiles over the pipe cross section were clearly seen with maximum flow rates near the centre of the pipe and low flow rate at the pipe wall (typically rubber pipe with reference concrete without silica fume and/or stabilizers). More plug-shaped profiles, with long slip layers and less variation of flow rate over the cross section, were also seen (typically in smooth acrylic pipes). Flow rate, amount of concrete sticking to the wall after flow and SEM-images of pipe surface roughness were observed, illustrating the problem of testing full scale pumping. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.bledco.com/business/Rouiba/education/Enseignement-universitaire/ECOLE [...] Fracture of concrete structure using simplified meshless method / Y. Dong in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009)
[article]
in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 966–972
Titre : Fracture of concrete structure using simplified meshless method Type de document : texte imprimé Auteurs : Y. Dong, Auteur ; S. Fang, Auteur ; Y. Zhang, Auteur Année de publication : 2009 Article en page(s) : pp. 966–972 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Computational mechanics; Crack; racture; Meshless; EFG; Material failure; Concrete; Enrichment; Partition of unity Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Numerical analysis of fracture in concrete is studied with a simplified meshless method. In this meshless method, the crack is represented by a set of disconnected cohesive crack segments that are required to pass through meshless nodes. The crack method therefore falls in the category of discrete crack methods. However, in contrast to most other methods where the crack is represented as continuous line/surface, no representation of the crack surface is needed. Hence, there is no need to track the crack path. Branching cracks and coalescing cracks are a natural outcome of the analysis and no specific algorithms need to be incorporated to model such complicated events. Besides the simplicity of the method, the accuracy is maintained. This is demonstrated through several examples. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001458 [article] Fracture of concrete structure using simplified meshless method [texte imprimé] / Y. Dong, Auteur ; S. Fang, Auteur ; Y. Zhang, Auteur . - 2009 . - pp. 966–972.
Génie Civil
Langues : Anglais (eng)
in Cement and concrete research > Vol. 39 N° 10 (Octobre 2009) . - pp. 966–972
Mots-clés : Computational mechanics; Crack; racture; Meshless; EFG; Material failure; Concrete; Enrichment; Partition of unity Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Numerical analysis of fracture in concrete is studied with a simplified meshless method. In this meshless method, the crack is represented by a set of disconnected cohesive crack segments that are required to pass through meshless nodes. The crack method therefore falls in the category of discrete crack methods. However, in contrast to most other methods where the crack is represented as continuous line/surface, no representation of the crack surface is needed. Hence, there is no need to track the crack path. Branching cracks and coalescing cracks are a natural outcome of the analysis and no specific algorithms need to be incorporated to model such complicated events. Besides the simplicity of the method, the accuracy is maintained. This is demonstrated through several examples. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001458 Fundamental mechanisms for polycarboxylate intercalation into C3A hydrate phases and the role of sulfate present in cement / Johann Plank in Cement and concrete research, Vol. 40 N° 1 (Janvier 2010)
[article]
in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 45-57
Titre : Fundamental mechanisms for polycarboxylate intercalation into C3A hydrate phases and the role of sulfate present in cement Type de document : texte imprimé Auteurs : Johann Plank, Auteur ; Dai Zhimin, Auteur ; Helena Keller, Auteur Article en page(s) : pp. 45-57 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Cement Polymers Concrete Admixture Organo-mineral phase Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : The fundamental reactions leading to the intercalation of polycarboxylate (PC) superplasticizers into calcium aluminum hydrates were studied by hydration of pure C3A in the presence of PC at 75 °C. It was found that the amount of dissolved sulfate present in cement pore solution determines whether organo-mineral phases are formed or not. In the absence of sulfate, PCs easily intercalate during C3A hydration in alkaline solution. Under these conditions, only excessive steric size of the PC will prevent intercalation. At low sulfate concentrations (SO42−/C3A molar ratios of 0.1–0.35), PC intercalates with intersalated alkali sulfate, are formed. At high sulfate concentrations (SO42−/C3A molar ratios of 0.7–2), PC can no longer intercalate. Instead, sulfate, because of its higher negative charge density, fills the interlayer space and monosulfoaluminates with different water contents are formed.
Anion exchange experiments confirm that from the initially formed C4AH13, PC will exchange the interlayer OH− anion whereas with monosulfoaluminates, no replacement of sulfate by PC was found. Consequently, in alkaline solution, PC intercalates will not exchange their PC against OH− anions whereas sulfate will gradually replace the PC.
Generally, intercalation of PC is an unwanted process because it consumes superplasticizer which is effective only when it adsorbs onto the cationic surfaces of AFm and AFt phases. Our experiments demonstrate that intercalation can be avoided by using PCs with long side chains or highly sulfated cements (SO42−/C3A molar ratio ≥ 0.75) containing alkali or calcium sulfates which dissolve fast. In undersulfated cements, however, PC intercalates can be formed, either directly during the stacking process of the [Ca2Al(OH)6]+ main layer, with PC acting as the template which determines the interlayer distance, or by anion exchange between initially formed aluminate hydrates (e.g. C4AH13 or C2AH8) and the PC anion.
DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4X7FRPX-3&_user=6 [...] [article] Fundamental mechanisms for polycarboxylate intercalation into C3A hydrate phases and the role of sulfate present in cement [texte imprimé] / Johann Plank, Auteur ; Dai Zhimin, Auteur ; Helena Keller, Auteur . - pp. 45-57.
Génie Civil
Langues : Anglais (eng)
in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 45-57
Mots-clés : Cement Polymers Concrete Admixture Organo-mineral phase Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : The fundamental reactions leading to the intercalation of polycarboxylate (PC) superplasticizers into calcium aluminum hydrates were studied by hydration of pure C3A in the presence of PC at 75 °C. It was found that the amount of dissolved sulfate present in cement pore solution determines whether organo-mineral phases are formed or not. In the absence of sulfate, PCs easily intercalate during C3A hydration in alkaline solution. Under these conditions, only excessive steric size of the PC will prevent intercalation. At low sulfate concentrations (SO42−/C3A molar ratios of 0.1–0.35), PC intercalates with intersalated alkali sulfate, are formed. At high sulfate concentrations (SO42−/C3A molar ratios of 0.7–2), PC can no longer intercalate. Instead, sulfate, because of its higher negative charge density, fills the interlayer space and monosulfoaluminates with different water contents are formed.
Anion exchange experiments confirm that from the initially formed C4AH13, PC will exchange the interlayer OH− anion whereas with monosulfoaluminates, no replacement of sulfate by PC was found. Consequently, in alkaline solution, PC intercalates will not exchange their PC against OH− anions whereas sulfate will gradually replace the PC.
Generally, intercalation of PC is an unwanted process because it consumes superplasticizer which is effective only when it adsorbs onto the cationic surfaces of AFm and AFt phases. Our experiments demonstrate that intercalation can be avoided by using PCs with long side chains or highly sulfated cements (SO42−/C3A molar ratio ≥ 0.75) containing alkali or calcium sulfates which dissolve fast. In undersulfated cements, however, PC intercalates can be formed, either directly during the stacking process of the [Ca2Al(OH)6]+ main layer, with PC acting as the template which determines the interlayer distance, or by anion exchange between initially formed aluminate hydrates (e.g. C4AH13 or C2AH8) and the PC anion.
DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4X7FRPX-3&_user=6 [...] Hydration of calcium sulfoaluminate cement by a ZnCl2 solution: Investigation at early age / Stéphane Bergera in Cement and concrete research, Vol. 39 N° 12 (Décembre 2009)
[article]
in Cement and concrete research > Vol. 39 N° 12 (Décembre 2009) . - pp. 1180-1187
Titre : Hydration of calcium sulfoaluminate cement by a ZnCl2 solution: Investigation at early age Type de document : texte imprimé Auteurs : Stéphane Bergera, Auteur ; Céline Cau Dit Coumes, Auteur ; Patrick Le Bescop, Auteur Année de publication : 2010 Article en page(s) : pp. 1180-1187 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sulfialuminate; Hydration; Zinc; Waste management; Calorimetry Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Hydration of calcium sulfoaluminate cement at early age was investigated as a function of the gypsum content of the binder, the thermal history of the material, and the ZnCl2 concentration in the mixing solution. Early hydration was strongly accelerated by the presence of gypsum, but lower percentages of reaction were reached after 24 h. The slowing down effect induced by ZnCl2, even at a concentration as high as 0.5 mol/L, was moderated compared to OPC but had a greater intensity in the absence of gypsum. Unlike what would have been expected for Portland cement, it was shown that the delay of a gypsum-free calcium sulfoaluminate cement resulted from the strong retardation caused by chloride anions, which was partly compensated by the accelerating effect of Zn2+ cations. The mineralogical observations revealed the precipitation of chloro–AFm phases such as Friedel's and Kuzel's salts, but no crystallized zinc-containing phases could be identified by XRD. The thermal history of the samples proved to be a key parameter. Applying a thermal cycle which reproduced the temperature rise and decrease occurring in a massive mortar block accelerated the rate of hydration and mainly modified the proportion of AFt versus AFm hydrates, especially when the binder had a gypsum content below 20%. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S000888460900204X [article] Hydration of calcium sulfoaluminate cement by a ZnCl2 solution: Investigation at early age [texte imprimé] / Stéphane Bergera, Auteur ; Céline Cau Dit Coumes, Auteur ; Patrick Le Bescop, Auteur . - 2010 . - pp. 1180-1187.
Génie Civil
Langues : Anglais (eng)
in Cement and concrete research > Vol. 39 N° 12 (Décembre 2009) . - pp. 1180-1187
Mots-clés : Sulfialuminate; Hydration; Zinc; Waste management; Calorimetry Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Hydration of calcium sulfoaluminate cement at early age was investigated as a function of the gypsum content of the binder, the thermal history of the material, and the ZnCl2 concentration in the mixing solution. Early hydration was strongly accelerated by the presence of gypsum, but lower percentages of reaction were reached after 24 h. The slowing down effect induced by ZnCl2, even at a concentration as high as 0.5 mol/L, was moderated compared to OPC but had a greater intensity in the absence of gypsum. Unlike what would have been expected for Portland cement, it was shown that the delay of a gypsum-free calcium sulfoaluminate cement resulted from the strong retardation caused by chloride anions, which was partly compensated by the accelerating effect of Zn2+ cations. The mineralogical observations revealed the precipitation of chloro–AFm phases such as Friedel's and Kuzel's salts, but no crystallized zinc-containing phases could be identified by XRD. The thermal history of the samples proved to be a key parameter. Applying a thermal cycle which reproduced the temperature rise and decrease occurring in a massive mortar block accelerated the rate of hydration and mainly modified the proportion of AFt versus AFm hydrates, especially when the binder had a gypsum content below 20%. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S000888460900204X Identification of viscoelastic C-S-H behavior in mature cement paste by FFT-based homogenization method / Vít Smilauer in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010)
PermalinkImpact resistance of poly (vinyl alcohol) fiber reinforced high-performance organic aggregate cementitious material / Bo Xu in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010)
PermalinkInfluence of aggregate size and volume fraction on shrinkage induced micro-cracking of concrete and mortar / Peter Grassl in Cement and concrete research, Vol. 40 N° 1 (Janvier 2010)
PermalinkInfluence of bleed water reabsorption on cement paste autogenous deformation / B.J. Mohr in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010)
PermalinkInfluence of free water on the quasi-static and dynamic strength of concrete in confined compression tests / P. Forquin in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010)
PermalinkInteraction between α-calcium sulfate hemihydrate and superplasticizer from the point of adsorption characteristics, hydration and hardening process / Baohong Guan in Cement and concrete research, Vol. 40 N° 2 (02 ex.) (Fevrier 2010)
PermalinkInternal curing of engineered cementitious composites for prevention of early age autogenous shrinkage cracking / Mustafa Şahmaran in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009)
PermalinkPermalinkMeasuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting / Nicolas Robeyst in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009)
PermalinkMeasuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting / Nicolas Robeyst in Cement and concrete research, Vol. 39 N° 10 (Octobre 2009)
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