ABSTRACT The stereological method of total projection was practically not applied yet because of the difficulty to use it manually. Yet, determinist, it is more precise than the oriented secants technique which is statistic. The author... more
ABSTRACT The stereological method of total projection was practically not applied yet because of the difficulty to use it manually. Yet, determinist, it is more precise than the oriented secants technique which is statistic. The author shows how it may be applied to the study of microcracking in concrete, providing its computerization.
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In the first part, the definition and the methods for estimating the coefficient of activity of a mineral filler are presented. The calculation relies on predictive laws of strength, here Bolomey's and Feret's laws. In the... more
In the first part, the definition and the methods for estimating the coefficient of activity of a mineral filler are presented. The calculation relies on predictive laws of strength, here Bolomey's and Feret's laws. In the second part, experimental results concerning the strength of mortars allow us to calculate the coefficient of activity of a fly ash. It is shown that it is not realistic to characterise the activity of the fly ash by a unique coefficient because the strength of mortars is not accordant with a linear law of the substitution ratio. Therefore, it is necessary to evaluate the coefficient of activity as a function of the substitution ratio.
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Presentation d'une methode d'investigation evitant la dessiccation, methode dite de simple replique, par duplication de la surface etudiee sur un film de bioden, permettant l'observation par microscope electronique a balayage... more
Presentation d'une methode d'investigation evitant la dessiccation, methode dite de simple replique, par duplication de la surface etudiee sur un film de bioden, permettant l'observation par microscope electronique a balayage (1000 angstrom). etude du beton a 28 jours de conservation en chambre humide. Methodes stereologiques de quantification des reseaux microfissuraux (automatisation permettant saisie et analyse). etude de l'evolution de la microfissuration sous charge, reliant degre de reversibilite et surface specifique de microfissuration (notion de "picofissuration")
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ABSTRACT
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... Sc. Paris t. 275 (1972), p. 1467. B. Perrin, JC Maso, J. Farran and R. Javelas, Existence d'une auréole de transition entre les granulats d'un mortier ou d'un béton et la masse de la pâte de ciment hydraté.... more
... Sc. Paris t. 275 (1972), p. 1467. B. Perrin, JC Maso, J. Farran and R. Javelas, Existence d'une auréole de transition entre les granulats d'un mortier ou d'un béton et la masse de la pâte de ciment hydraté. Conséquences sur les propriétés mécaniques, CR Ac. Sc. ...
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International audienc
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The aim of this paper is to assess the degradation of formaldehyde using various coatings, including photocatalytic dispersion. The experiments were conducted at a laboratory scale in a standardized photoreactor based on the procedure... more
The aim of this paper is to assess the degradation of formaldehyde using various coatings, including photocatalytic dispersion. The experiments were conducted at a laboratory scale in a standardized photoreactor based on the procedure described in the ISO 22197-4 standard. Various illuminations conditions were explored: UV and visible light. The dispersions tested were applied to common building materials using a coating method. The abatement values were determined by high performance liquid chromatography according to ISO 16000-3 standard. Results showed that parameters such as nature of substrate, type of dispersion and product layer thickness on surface played an important role. Moreover, formaldehyde adsorption on substrate was observed. This phenomenon was far from being negligible and contributed to decrease formaldehyde concentration. Limiting the amount of formaldehyde in indoor environment is a necessary priority for the modern society as this gas known as being carcinogen diminishes the life quality of occupants and poses serious health risks.
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ABSTRACT Flocculation and deflocculation have a fundamental role to play in the use of mortar and concrete. In order to monitor these phenomena more fully, we need to have a better understanding of the structure of fresh cement paste. The... more
ABSTRACT Flocculation and deflocculation have a fundamental role to play in the use of mortar and concrete. In order to monitor these phenomena more fully, we need to have a better understanding of the structure of fresh cement paste. The work presented in this publication is part of the process of meeting this need. By applying a technique of cryosublimation together with epoxy resin impregnation to fresh cement paste samples, we can obtain SEM images of test-piece cross-sections where the initial arrangement of anhydrous cement grains is modified neither by hydration nor by experimental procedure. Paste structure can thus be investigated by quantitative image analysis. By using a new method of image processing during filtering and binarization, we can obtain a binary image which faithfully reproduces the original image and on which we can then carry out geometrical parameter measurements.
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The recycling of asphalt is a process where old pavement is broken up and used as reclaimed asphalt pavement (RAP) in new asphalt pavement, often with the aid of recycling agents. The goal of asphalt recycling agents is to reintroduce the... more
The recycling of asphalt is a process where old pavement is broken up and used as reclaimed asphalt pavement (RAP) in new asphalt pavement, often with the aid of recycling agents. The goal of asphalt recycling agents is to reintroduce the properties lost in bitumen and asphalt during aging such as penetration, softening point, viscosity, ductility, cohesion and adhesion to aggregate, reducing the performance of asphalt and requiring its replacement. The purpose of this study is to observe the chemistry of bitumen aging and the effects of recycling agents may have in reversing it. Fourier transform infrared spectroscopy (FTIR)-attenuated total reflectance (ATR) was used to analyse the bitumen aging and regeneration in terms of the evolution of carbonyl, sulfoxide and other bands. FTIR-ATR microscopy was used to study the distribution of these bands between the aggregates in order to understand the remobilization of the old asphalt (RAP) by the recycling agents through observing their penetration into the RAP. A method for aging bitumen and mastic in a ventilated oven was developed. An increase in C=O and S=O indices was observed with aging, plateauing after 7d.
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ABSTRACT Flocculation and deflocculation have a fundamental role to play in the use of mortar and concrete. In order to monitor these phenomena more fully, we need to have a better understanding of the structure of fresh cement paste. The... more
ABSTRACT Flocculation and deflocculation have a fundamental role to play in the use of mortar and concrete. In order to monitor these phenomena more fully, we need to have a better understanding of the structure of fresh cement paste. The work presented in this publication is part of the process of meeting this need. By applying a technique of cryosublimation together with epoxy resin impregnation to fresh cement paste samples, we can obtain SEM images of test-piece cross-sections where the initial arrangement of anhydrous cement grains is modified neither by hydration nor by experimental procedure. Paste structure can thus be investigated by quantitative image analysis. By using a new method of image processing during filtering and binarization, we can obtain a binary image which faithfully reproduces the original image and on which we can then carry out geometrical parameter measurements.
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The ion diffusion process in mortar is different from the one which occurs in cement paste. This difference is due to the presence of transition zones, which take place around the grains in mortar and which are very porous regions. Based... more
The ion diffusion process in mortar is different from the one which occurs in cement paste. This difference is due to the presence of transition zones, which take place around the grains in mortar and which are very porous regions. Based on mercury intrusion porosimetry experimental data and on the analysis of percolation through a 3D mortar model, a computation
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This work is the second part of an overall project, the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures. The first part presented the separation of the different... more
This work is the second part of an overall project, the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures. The first part presented the separation of the different physical effects responsible for changes in cement hydration when chemically inert quartz powders are used in mortars. This second part describes
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La connaissance de la microstructure de la pate de ciment permet de mieux comprendre les proprietes physiques et mecaniques des produits derives (beton, mortier ...). L'observation au microscope electronique a balayage (MEB), bien... more
La connaissance de la microstructure de la pate de ciment permet de mieux comprendre les proprietes physiques et mecaniques des produits derives (beton, mortier ...). L'observation au microscope electronique a balayage (MEB), bien maitrisee maintenant grace a la technique de cryosublimation, donne naissance a un nouvel outil de quantification a l'usage de l'industrie chimique et cimentiere. Cet article presente les differentes etapes du traitement des images obtenues pour caracteriser - entre autres - en fonction du rapport Eau-Ciment (E/C) la dispersion eminemment variable des grains anhydres de ciment dans une pate figee des la preparation. (A). (Titres en anglais et allemand : Microstructural characterization of e fresh cement paste ; Kennzeichnende Mikrostruktur eines Frischen Zementleims).
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This paper describes a research program aimed at establishing the factors that give a good durability to pavement repairs made with metallic fiber-reinforced concrete. The experimental study shows that fibers, as they do not significantly... more
This paper describes a research program aimed at establishing the factors that give a good durability to pavement repairs made with metallic fiber-reinforced concrete. The experimental study shows that fibers, as they do not significantly reduce the shrinkage of concrete, have a positive effect by enhancing its relaxation and creep capacity. Conversely, the indirect effects of cracking which may be of major importance must not be ignored. A finite element study shows that, among these effects, the stresses induced by the passage of vehicles, very dependent on the cracking characteristics, give a significant advantage to the fiber reinforced overlays.
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This paper deals with the degradation of NO by photocatalytic oxidation using TiO2-based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored... more
This paper deals with the degradation of NO by photocatalytic oxidation using TiO2-based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored to evaluate their influence on photocatalysis efficiency: TiO2 dry matter content applied to the surface, nature of the substrate, and illumination conditions (UV and visible light). This article points out the different behaviors between three kinds of substrates which are common building materials: normalized mortar, denser mortar, and commercial wood. The illumination conditions are of great importance in the photocatalytic process with experiments under UV light showing the best results. However, a significant decrease in NO concentration under visible light is also observed provided that the TiO2 dry matter content on the surface is high enough. The nature of the substrate plays an important role in the photocatalytic activity with rougher sub...
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This paper describes a research program aimed at establishing the factors that give a good durability to pavement repairs made with metallic fiber-reinforced concrete. The experimental study shows that fibers, as they do not significantly... more
This paper describes a research program aimed at establishing the factors that give a good durability to pavement repairs made with metallic fiber-reinforced concrete. The experimental study shows that fibers, as they do not significantly reduce the shrinkage of concrete, have a positive effect by enhancing its relaxation and creep capacity. Conversely, the indirect effects of cracking which may be of major importance must not be ignored. A finite element study shows that, among these effects, the stresses induced by the passage of vehicles, very dependent on the cracking characteristics, give a significant advantage to the fiber reinforced overlays.
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... Sc. Paris t. 275 (1972), p. 1467. B. Perrin, JC Maso, J. Farran and R. Javelas, Existence d'une auréole de transition entre les granulats d'un mortier ou d'un béton et la masse de la pâte de ciment hydraté.... more
... Sc. Paris t. 275 (1972), p. 1467. B. Perrin, JC Maso, J. Farran and R. Javelas, Existence d'une auréole de transition entre les granulats d'un mortier ou d'un béton et la masse de la pâte de ciment hydraté. Conséquences sur les propriétés mécaniques, CR Ac. Sc. ...
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Apercu des contributions des laboratoires universitaires et des enseignants chercheurs au transfert des connaissances et a l'innovation pour le developpement et l'amelioration des travaux publics. Description des techniques... more
Apercu des contributions des laboratoires universitaires et des enseignants chercheurs au transfert des connaissances et a l'innovation pour le developpement et l'amelioration des travaux publics. Description des techniques suivantes, qui representent la concretisation de ces contibutions : colorimetrie des parements de beton ; prediction du comportement mecanique des ouvrages en beton arme degrades par la corrosion des armatures ; reparation par rechargement mince adherent de dallages industriels ou chaussees en beton ; evaluation de la degradation de la peau du beton par ondes ultrasonores ; ondes et turbulences ; le Geomecametre (marque deposee), nouvel appareil d'essais in situ ; de l'etude de la pollution des sols non satures. Utilisation de la methode TDR (Time Domain Reflectometry) ; etude de l'interaction creusement de tunnels-ouvrages existants ; analyse du comportement dynamique des micropieux utilises comme des elements de fondation.
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The purpose of this thesis was about the control of the aesthetic quality of the concrete surfaces and had as main goals : - to develop a tool of qualification of aesthetic surfaces ; - to evaluate the influence of the parameters of put... more
The purpose of this thesis was about the control of the aesthetic quality of the concrete surfaces and had as main goals : - to develop a tool of qualification of aesthetic surfaces ; - to evaluate the influence of the parameters of put in place of the concrete ; - to evaluate the influence of the parameters of concrete formulations ; - to describe the microstructure of the defects.