Dépouillements

Hydration in high-performance cementitious systems containing vitreous calcium aluminosilicate or silica fume / Narayanan Neithalath in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 473–481 Titre : Hydration in high-performance cementitious systems containing vitreous calcium aluminosilicate or silica fume Type de document : texte imprimé Auteurs : Narayanan Neithalath, Auteur ; Jarrod Persun, Auteur ; Akhter Hossain, Auteur Année de publication : 2009 Article en page(s) : pp. 473–481 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Hydration  ;  Degree  of  hydration  ;  Silica  fume  ;  Porosity;  Vitreous  calcium  aluminosilicate;  Non-evaporable  water  content Résumé : The influence of a relatively new high-performance cement replacement material—vitreous calcium aluminosilicate (VCAS)—on the hydration behavior in cementitious systems, and its comparison to silica fume (SF) are presented in this paper. VCAS is shown to have no cementitious qualities, but exhibits significant pozzolanicity, which has been quantified using strength activity index and electrical conductivity change. VCAS modified pastes are found to consume more water during hydration than the corresponding SF modified pastes. Based on a normalized calcium hydroxide content defined in this paper, it is seen that the pozzolanic reaction of VCAS does not happen until 7 days while that of SF occurs as early as the first day. The degrees of hydration of the modified pastes are predicted using a model that employs the change in non-evaporable water resulting from the use of these replacement materials. VCAS modified pastes show lower later age porosities as compared to the plain and SF modified pastes. However, at equal degrees of hydration, SF modified pastes show the lowest porosity. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000556 [article] Hydration in high-performance cementitious systems containing vitreous calcium aluminosilicate or silica fume [texte imprimé] / Narayanan Neithalath, Auteur ; Jarrod Persun, Auteur ; Akhter Hossain, Auteur . - 2009 . - pp. 473–481. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 473–481 Mots-clés : Hydration  ;  Degree  of  hydration  ;  Silica  fume  ;  Porosity;  Vitreous  calcium  aluminosilicate;  Non-evaporable  water  content Résumé : The influence of a relatively new high-performance cement replacement material—vitreous calcium aluminosilicate (VCAS)—on the hydration behavior in cementitious systems, and its comparison to silica fume (SF) are presented in this paper. VCAS is shown to have no cementitious qualities, but exhibits significant pozzolanicity, which has been quantified using strength activity index and electrical conductivity change. VCAS modified pastes are found to consume more water during hydration than the corresponding SF modified pastes. Based on a normalized calcium hydroxide content defined in this paper, it is seen that the pozzolanic reaction of VCAS does not happen until 7 days while that of SF occurs as early as the first day. The degrees of hydration of the modified pastes are predicted using a model that employs the change in non-evaporable water resulting from the use of these replacement materials. VCAS modified pastes show lower later age porosities as compared to the plain and SF modified pastes. However, at equal degrees of hydration, SF modified pastes show the lowest porosity. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000556

Solid solution between Al-ettringite and Fe-ettringite (Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O) / Göril Möschner in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 482–489 Titre : Solid solution between Al-ettringite and Fe-ettringite (Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O) Type de document : texte imprimé Auteurs : Göril Möschner, Auteur ; Barbara Lothenbach, Auteur ; Frank Winnefeld, Auteur Année de publication : 2009 Article en page(s) : pp. 482–489 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Ettringite;  Thermodynamic  calculations;  Hydration  products Résumé : The solid solution between Al- and Fe-ettringite Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O was investigated. Ettringite phases were synthesized at different Al/(Al + Fe)-ratios (= XAl,total), so that XAl increased from 0.0 to 1.0 in 0.1 unit steps. After 8 months of equilibration, the solid phases were analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), while the aqueous solutions were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). XRD analyses of the solid phases indicated the existence of a miscibility gap between XAl,total = 0.3–0.6. Some of the XRD reflections showed two overlapping peaks at these molar ratios. The composition of the aqueous solutions, however, would have been in agreement with both, the existence of a miscibility gap or a continuous solid solution between Al- and Fe-ettringite, based on thermodynamic modeling, simulating the experimental conditions. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000490 [article] Solid solution between Al-ettringite and Fe-ettringite (Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O) [texte imprimé] / Göril Möschner, Auteur ; Barbara Lothenbach, Auteur ; Frank Winnefeld, Auteur . - 2009 . - pp. 482–489. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 482–489 Mots-clés : Ettringite;  Thermodynamic  calculations;  Hydration  products Résumé : The solid solution between Al- and Fe-ettringite Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O was investigated. Ettringite phases were synthesized at different Al/(Al + Fe)-ratios (= XAl,total), so that XAl increased from 0.0 to 1.0 in 0.1 unit steps. After 8 months of equilibration, the solid phases were analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), while the aqueous solutions were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). XRD analyses of the solid phases indicated the existence of a miscibility gap between XAl,total = 0.3–0.6. Some of the XRD reflections showed two overlapping peaks at these molar ratios. The composition of the aqueous solutions, however, would have been in agreement with both, the existence of a miscibility gap or a continuous solid solution between Al- and Fe-ettringite, based on thermodynamic modeling, simulating the experimental conditions. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000490

Chemo–mechanical modeling for prediction of alkali silica reaction (ASR) expansion / Stéphane Multon in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. Martin Cyr Titre : Chemo–mechanical modeling for prediction of alkali silica reaction (ASR) expansion Type de document : texte imprimé Auteurs : Stéphane Multon, Auteur ; Alain Sellier, Auteur ; Martin Cyr, Auteur Année de publication : 2009 Article en page(s) : pp. Martin Cyr Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Alkali-silica  reaction  (ASR);  Particle  size;  Alkali  content;  Expansion;  Model Résumé : The effect of the size of the aggregate on ASR expansion has already been well illustrated. This paper presents a microscopic model to analyze the development of ASR expansion of mortars containing reactive aggregate of different sizes. The attack of the reactive silica by alkali was determined through the mass balance equation, which controls the diffusion mechanism in the aggregate and the fixation of the alkali in the ASR gels. The mechanical part of the model is based on the damage theory in order to assess the decrease of stiffness of the mortar due to cracking caused by ASR and to calculate the expansion of a Representative Elementary Volume (REV) of concrete. Parameters of the model were estimated by curve fitting the expansions of four experimental mortars. The paper shows that the decrease of expansion with the size of the aggregate and the increase of the expansion with the alkali content are reproduced by the model, which is able to predict the expansions of six other mortars containing two sizes of reactive aggregate and cast with two alkali contents. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000702 [article] Chemo–mechanical modeling for prediction of alkali silica reaction (ASR) expansion [texte imprimé] / Stéphane Multon, Auteur ; Alain Sellier, Auteur ; Martin Cyr, Auteur . - 2009 . - pp. Martin Cyr. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. Martin Cyr Mots-clés : Alkali-silica  reaction  (ASR);  Particle  size;  Alkali  content;  Expansion;  Model Résumé : The effect of the size of the aggregate on ASR expansion has already been well illustrated. This paper presents a microscopic model to analyze the development of ASR expansion of mortars containing reactive aggregate of different sizes. The attack of the reactive silica by alkali was determined through the mass balance equation, which controls the diffusion mechanism in the aggregate and the fixation of the alkali in the ASR gels. The mechanical part of the model is based on the damage theory in order to assess the decrease of stiffness of the mortar due to cracking caused by ASR and to calculate the expansion of a Representative Elementary Volume (REV) of concrete. Parameters of the model were estimated by curve fitting the expansions of four experimental mortars. The paper shows that the decrease of expansion with the size of the aggregate and the increase of the expansion with the alkali content are reproduced by the model, which is able to predict the expansions of six other mortars containing two sizes of reactive aggregate and cast with two alkali contents. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000702

Cement and Concrete Research Volume 39, Issue 6, June 2009, Pages 501–509 Cover image Study of mineralogy and leaching behavior of stabilized/solidified sludge using differential acid neutralization analysis: Part II: Use of numerical simulation as an aid tool for cementitious hydrates identification / O. Peyronnard in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. Titre : Cement and Concrete Research Volume 39, Issue 6, June 2009, Pages 501–509 Cover image Study of mineralogy and leaching behavior of stabilized/solidified sludge using differential acid neutralization analysis: Part II: Use of numerical simulation as an aid tool for cementitious hydrates identification Type de document : texte imprimé Auteurs : O. Peyronnard, Auteur ; D. Blanc, Auteur ; M. Benzaazoua, Auteur Année de publication : 2009 Article en page(s) : pp. Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Waste  management  ;  Modeling  ;  Mineral  assemblage;  Fly  ash  ;  Portland  cement Résumé : In this work, we propose a methodology coupling differential acid neutralization analysis, chemical analysis of selected leachates and numerical simulation to identify the minerals controlling the leaching behavior of stabilized hydroxide sludge. This second part deals with the use of numerical simulation as an aid tool for the identification of the minerals. The framework for minerals identification is based on the study of minerals stability in function of the geochemical context using numerical simulation. A mineral assemblage permitting the simulation of a pH dependence leaching test (acid neutralization and release of elements) has been identified for the four studied cement pastes. Therefore, the proposed methodology is a pertinent tool for the modeling of the leaching behavior of inorganic wastes. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S000888460900074X [article] Cement and Concrete Research Volume 39, Issue 6, June 2009, Pages 501–509 Cover image Study of mineralogy and leaching behavior of stabilized/solidified sludge using differential acid neutralization analysis: Part II: Use of numerical simulation as an aid tool for cementitious hydrates identification [texte imprimé] / O. Peyronnard, Auteur ; D. Blanc, Auteur ; M. Benzaazoua, Auteur . - 2009 . - pp. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. Mots-clés : Waste  management  ;  Modeling  ;  Mineral  assemblage;  Fly  ash  ;  Portland  cement Résumé : In this work, we propose a methodology coupling differential acid neutralization analysis, chemical analysis of selected leachates and numerical simulation to identify the minerals controlling the leaching behavior of stabilized hydroxide sludge. This second part deals with the use of numerical simulation as an aid tool for the identification of the minerals. The framework for minerals identification is based on the study of minerals stability in function of the geochemical context using numerical simulation. A mineral assemblage permitting the simulation of a pH dependence leaching test (acid neutralization and release of elements) has been identified for the four studied cement pastes. Therefore, the proposed methodology is a pertinent tool for the modeling of the leaching behavior of inorganic wastes. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S000888460900074X

Why is fresh self-compacting concrete shear thickening? / Dimitri Feys in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 510–523 Titre : Why is fresh self-compacting concrete shear thickening? Type de document : texte imprimé Auteurs : Dimitri Feys, Auteur ; Ronny Verhoeven, Auteur ; Geert De Schutter, Auteur Année de publication : 2009 Article en page(s) : pp. 510–523 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Fresh  self-compacting  concrete;  Rheology;  Shear  thickening;  Cluster Résumé : The rheological properties of fresh concrete are mostly described by means of the Bingham model. For self-compacting concrete, the Bingham model is applicable in a lot of cases, but some authors report that the rheological behaviour is non-linear. The apparent viscosity increases with increasing shear rate and the SCC shows shear thickening behaviour. Shear thickening becomes important in operations occurring at high shear rates, like mixing and pumping. In these cases, shear thickening should not be forgotten in order to avoid breaking of the mixer, pump or pipes. This paper will describe two possible theories for shear thickening behaviour of SCC, based on results published in the rheology literature. The first theory consists of the formation of so-called (hydro-)clusters, which are temporary assemblies of small particles. These clusters start being formed from a certain shear stress on: the critical shear stress. They cause the viscosity to increase with increasing shear rate. A second theory is based on grain inertia, where a part of the shearing force is transmitted through direct momentum transfer between solid particles. Results on cement pastes prove that the grain inertia theory is not the main cause of shear thickening in self-compacting concrete. The influence of several parameters on the shear thickening behaviour of SCC can be well explained by means of the cluster theory. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000544 [article] Why is fresh self-compacting concrete shear thickening? [texte imprimé] / Dimitri Feys, Auteur ; Ronny Verhoeven, Auteur ; Geert De Schutter, Auteur . - 2009 . - pp. 510–523. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 510–523 Mots-clés : Fresh  self-compacting  concrete;  Rheology;  Shear  thickening;  Cluster Résumé : The rheological properties of fresh concrete are mostly described by means of the Bingham model. For self-compacting concrete, the Bingham model is applicable in a lot of cases, but some authors report that the rheological behaviour is non-linear. The apparent viscosity increases with increasing shear rate and the SCC shows shear thickening behaviour. Shear thickening becomes important in operations occurring at high shear rates, like mixing and pumping. In these cases, shear thickening should not be forgotten in order to avoid breaking of the mixer, pump or pipes. This paper will describe two possible theories for shear thickening behaviour of SCC, based on results published in the rheology literature. The first theory consists of the formation of so-called (hydro-)clusters, which are temporary assemblies of small particles. These clusters start being formed from a certain shear stress on: the critical shear stress. They cause the viscosity to increase with increasing shear rate. A second theory is based on grain inertia, where a part of the shearing force is transmitted through direct momentum transfer between solid particles. Results on cement pastes prove that the grain inertia theory is not the main cause of shear thickening in self-compacting concrete. The influence of several parameters on the shear thickening behaviour of SCC can be well explained by means of the cluster theory. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000544

SCC formwork pressure: Influence of steel rebars / A. Perrot in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 524–528 Titre : SCC formwork pressure: Influence of steel rebars Type de document : texte imprimé Auteurs : A. Perrot, Auteur ; S. Amziane, Auteur ; Ovarlez, G., Auteur Année de publication : 2009 Article en page(s) : pp. 524–528 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Fresh  concrete;  Rheology;  Workability;  Formwork  presure;  Thixotropy Résumé : The formwork pressure exerted by a given Self Compacting Concrete (SCC) depends on its thixotropic behavior, on the casting rate and on the shape of the formwork. It can moreover be expected that, in the case of a formwork containing steel rebars, these should also play a role. In first part, the specific case of a cylindrical formwork containing a single cylindrical steel rebar is studied. In second part, a comparison of the theoretical predictions to the experimental measurements of the pressure drop, after the end of casting SCC, was determined and the proposed model was validated. Finally, an extrapolation is suggested of the proposed method to the case of a rectangular formwork containing a given horizontal section of steel rebars, which could allow the prediction of the formwork pressure during casting. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000519 [article] SCC formwork pressure: Influence of steel rebars [texte imprimé] / A. Perrot, Auteur ; S. Amziane, Auteur ; Ovarlez, G., Auteur . - 2009 . - pp. 524–528. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 524–528 Mots-clés : Fresh  concrete;  Rheology;  Workability;  Formwork  presure;  Thixotropy Résumé : The formwork pressure exerted by a given Self Compacting Concrete (SCC) depends on its thixotropic behavior, on the casting rate and on the shape of the formwork. It can moreover be expected that, in the case of a formwork containing steel rebars, these should also play a role. In first part, the specific case of a cylindrical formwork containing a single cylindrical steel rebar is studied. In second part, a comparison of the theoretical predictions to the experimental measurements of the pressure drop, after the end of casting SCC, was determined and the proposed model was validated. Finally, an extrapolation is suggested of the proposed method to the case of a rectangular formwork containing a given horizontal section of steel rebars, which could allow the prediction of the formwork pressure during casting. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000519

Investigating the thermo-mechanical behaviour of cementitious materials using image processing techniques / V. Huon in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 529–536 Titre : Investigating the thermo-mechanical behaviour of cementitious materials using image processing techniques Type de document : texte imprimé Auteurs : V. Huon, Auteur Année de publication : 2009 Article en page(s) : pp. 529–536 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Infrared  thermography;  Image  analysis;  Mechanical  properties;  Concrete;  High-performance  concrete Résumé : Infrared thermography and Digital Image Correlation were used to analyse the mechanical behaviour of mortar, concrete, and high-performance concrete specimens under quasi-static loads. For specimens under compressive loads, Infrared thermography clearly showed the thermo-elastic coupling as well as thermal dissipations due to the microcracking state of freeze/thaw damaged concrete specimens. During an up to failure compressive test, localized thermal effects were observed at the macro-crack location before it appeared. Strain fields at the surface of steel-fibre high-performance concrete specimens under tensile and flexural loadings were determined using the Digital Image Correlation (DIC) technique. These experiments showed that the strain fields early became inhomogeneous. Strains concentrated in multiple localization zones which highlighted the role of the steel fibres in transmitting the internal forces. REFERENCE : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000520 [article] Investigating the thermo-mechanical behaviour of cementitious materials using image processing techniques [texte imprimé] / V. Huon, Auteur . - 2009 . - pp. 529–536. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 529–536 Mots-clés : Infrared  thermography;  Image  analysis;  Mechanical  properties;  Concrete;  High-performance  concrete Résumé : Infrared thermography and Digital Image Correlation were used to analyse the mechanical behaviour of mortar, concrete, and high-performance concrete specimens under quasi-static loads. For specimens under compressive loads, Infrared thermography clearly showed the thermo-elastic coupling as well as thermal dissipations due to the microcracking state of freeze/thaw damaged concrete specimens. During an up to failure compressive test, localized thermal effects were observed at the macro-crack location before it appeared. Strain fields at the surface of steel-fibre high-performance concrete specimens under tensile and flexural loadings were determined using the Digital Image Correlation (DIC) technique. These experiments showed that the strain fields early became inhomogeneous. Strains concentrated in multiple localization zones which highlighted the role of the steel fibres in transmitting the internal forces. REFERENCE : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000520

Crack effects on gas and water permeability of concretes / Vincent Picandet in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 537–547 Titre : Crack effects on gas and water permeability of concretes Type de document : texte imprimé Auteurs : Vincent Picandet, Auteur ; Abdelhafid Khelidj, Auteur ; Hervé Bellegou, Auteur Année de publication : 2009 Article en page(s) : pp. 537–547 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Permeability;  Microcracking;  Durability;  High-performance  oncrete;  Fiber  reinforcement Résumé : The relationship between load-induced cracking and concrete permeability is studied. Ordinary concrete (OC) and high-performance concrete (HPC), including steel fiber-reinforced concrete (HPFRC), are used. Two discs, 50 mm-thick slices, cut from 110–220 mm cylindrical specimens are diametrically loaded, as for a normal splitting test. The lateral displacement, also called the crack opening displacement (COD) is monitored for each loading cycle. After unloading, gas and finally water permeability tests are both performed, using constant head permeameter, to compare the influence of the percolating fluid and the COD. Due to the wide range of measured gas flow, Klinkenberg's and Dupuit-Forcheimer's laws are applied to compute the intrinsic gas permeability. Results suggest it increases proportionally to the cube of the COD and it matches water permeability, if only the first water percolating time is considered. The roughness parameter of the cracks induced in each concrete, is compared and discussed. REFERENCE : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000696 [article] Crack effects on gas and water permeability of concretes [texte imprimé] / Vincent Picandet, Auteur ; Abdelhafid Khelidj, Auteur ; Hervé Bellegou, Auteur . - 2009 . - pp. 537–547. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 537–547 Mots-clés : Permeability;  Microcracking;  Durability;  High-performance  oncrete;  Fiber  reinforcement Résumé : The relationship between load-induced cracking and concrete permeability is studied. Ordinary concrete (OC) and high-performance concrete (HPC), including steel fiber-reinforced concrete (HPFRC), are used. Two discs, 50 mm-thick slices, cut from 110–220 mm cylindrical specimens are diametrically loaded, as for a normal splitting test. The lateral displacement, also called the crack opening displacement (COD) is monitored for each loading cycle. After unloading, gas and finally water permeability tests are both performed, using constant head permeameter, to compare the influence of the percolating fluid and the COD. Due to the wide range of measured gas flow, Klinkenberg's and Dupuit-Forcheimer's laws are applied to compute the intrinsic gas permeability. Results suggest it increases proportionally to the cube of the COD and it matches water permeability, if only the first water percolating time is considered. The roughness parameter of the cracks induced in each concrete, is compared and discussed. REFERENCE : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000696

Quantification of tortuosity in hardened cement pastes using synchrotron-based X-ray computed microtomography / M.A.B. Promentilla in Cement and concrete research, Vol. 39 N° 6 (Juin 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 548–557 Titre : Quantification of tortuosity in hardened cement pastes using synchrotron-based X-ray computed microtomography Type de document : texte imprimé Auteurs : M.A.B. Promentilla, Auteur ; T. Sugiyama, Auteur ; T. Hitomi, Auteur Année de publication : 2009 Article en page(s) : pp. 548–557 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Tortuosity;  Microstructure;  Cement  paste;  Synchrotron  microtomography;  Random  walk  simulation Résumé : Tortuosity, as being influenced by the 3D pore micro-geometry, is an important physical quantity to understand better the effect of pore structure on transport properties of cement-based materials. This study attempts to evaluate directly this pore structure-transport parameter from the microtomographic images at spatial resolution of 0.5 μm. This resolution, is by far, to our knowledge, the highest resolution reported for 3D non-invasive imaging of hardened cement pastes. The results show the feasibility of using synchrotron microtomography coupled with 3D image analysis and random walk simulation to measure the diffusion tortuosity that has a direct bearing on transport properties. The tortuosity associated with the percolating pore space seems to reflect the pore morphology that mainly controls the transport properties in young cement pastes; thus, explaining the rough agreement of the results with the computer model or experimental evidence. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000532 [article] Quantification of tortuosity in hardened cement pastes using synchrotron-based X-ray computed microtomography [texte imprimé] / M.A.B. Promentilla, Auteur ; T. Sugiyama, Auteur ; T. Hitomi, Auteur . - 2009 . - pp. 548–557. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 6 (Juin 2009) . - pp. 548–557 Mots-clés : Tortuosity;  Microstructure;  Cement  paste;  Synchrotron  microtomography;  Random  walk  simulation Résumé : Tortuosity, as being influenced by the 3D pore micro-geometry, is an important physical quantity to understand better the effect of pore structure on transport properties of cement-based materials. This study attempts to evaluate directly this pore structure-transport parameter from the microtomographic images at spatial resolution of 0.5 μm. This resolution, is by far, to our knowledge, the highest resolution reported for 3D non-invasive imaging of hardened cement pastes. The results show the feasibility of using synchrotron microtomography coupled with 3D image analysis and random walk simulation to measure the diffusion tortuosity that has a direct bearing on transport properties. The tortuosity associated with the percolating pore space seems to reflect the pore morphology that mainly controls the transport properties in young cement pastes; thus, explaining the rough agreement of the results with the computer model or experimental evidence. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000532

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