Fields of search interest- Technical control of cement's materials - Enrichment of industrial waste.- Formulation, characterization and durability of special concrete.
This paper reports an experimental study of the influence of marble powder used as partial substi... more This paper reports an experimental study of the influence of marble powder used as partial substitute for Portland cement (PC) on the mechanical properties and durability of high performance concretes. The analysis of the experimental results on concrete at 15% content of marble powder with a fineness modulus of 11500 cm 2 /g, in a chloride environment, showed that it contributes positively to the perfection of its mechanical characteristics, its durability with respect to migration of chloride ions and oxygen permeability. On the basis of the experiments performed, it can be concluded that the marble powder is suitable for formulation of high performance concretes (HPC) and their properties are significantly better compared to the reference concrete (RC).
American Journal of Civil Engineering and Architecture, Jul 5, 2016
The production of a high performance concrete (HPC) has expanded the scope use of concrete expose... more The production of a high performance concrete (HPC) has expanded the scope use of concrete exposed to aggressive environments, thanks to the limited porosity, the durability, the rheological, physical and mechanical properties with the respect remarkable to a conventional concrete. The objective of this study is to develop a HPC incorporating finely ground limestone. The results show that the substitution of one part of cement by limestone contributes more to the improvement of physical, mechanical and microstructural properties of concrete. The couple cement/limestone contributes significantly to a densification of the matrix unlike when the cement is not substituted by addition. The survey also shows that the limestone does not fall into any chemical reaction. However, the development of resistance (physical phenomenon), obviously depends on the quality of hydrates supplied by the hydration, but also how these hydrates are assembled, their arrangement in space and their connections.
Environnement, Ingénierie & Développement, 2021
The cement industry is a greenhouse gas-generatingactivity since approximately one ton of carbond... more The cement industry is a greenhouse gas-generatingactivity since approximately one ton of carbondioxide (CO2) is emitted into the atmosphere per tonof cement produced. Many mineral products can beadded to concrete to modify their technicalcharacteristics for particular applications and/or toimprove the environmental balance of their lifecycle. This article reports the study of the influenceof the addition of waste marble on the properties ofself-consolidating concrete (SCC). Several additionrates were tested Concrete were prepared with aWater/Binder (W/L) ratio of 0.33 and an equalPortland cement dosage of 400kg/m3. Used alone asa reference composition (white), or with additions ofmarble powder at dosages of 15, 20 and 30% relativeto the mass of the cement. The properties of theself-compacting concrete in the fresh and hardenedstate were tested using specific tests, by varying thefineness of the marble powder at 3000, 7000 and9000 cm2/g and the Superplasticizer content at 1 .5%and 1...
European Journal of Environmental and Civil Engineering, 2014
Most mechanical properties and durability of cementitious materials are related to the performanc... more Most mechanical properties and durability of cementitious materials are related to the performance of the hydrated cement that coats the granular skeleton. In this paper, concrete is formulated by substituting 30% of cement by finely ground glass powder. The experimental study consists of investigating the effect of conservation in tap water or sulphate water on the performance of concrete. The mechanisms of concrete damage have been related to the development of the microstructure of the material. The degradations were observed using scanning electron microscope (SEM) and quantified by X-ray diffraction (XRD). In addition, chloride ions permeability and gas permeability tests were performed. The results showed that glass powder presents a pozzolanic activity and hence it affects favourably the microstructure of the paste which becomes denser and less permeable.
Journal of building materials and structures, Mar 4, 2016
In this work, several reinforced self-compacting concretes were prepared by using three types of ... more In this work, several reinforced self-compacting concretes were prepared by using three types of fibers made of steel, polypropylene and glass, and three different types of mineral additions (marble powder, metakaolin and limestone powder). The water to cement ratio was kept constant at 0.34 and fibers were used in combination, keeping the total fiber content constant at 60 kg/m3. Slump flow diameter, L-Box, stability and air content were performed to assess the fresh properties of the concrete. Compressive strength, flexural strength, splitting tensile strength and ultrasonic pulse velocity of the concrete were determined for the hardened properties. Noteworthy performances were generally obtained, particularly in hardened properties for the self-compacting concretes prepared with steel fibers in association with polypropylene fiber and marble powder as mineral addition.
Certain finely ground mineral admixtures, such as blast furnace slag, pozzolana and limestone, in... more Certain finely ground mineral admixtures, such as blast furnace slag, pozzolana and limestone, influence, to a greater or lesser extent, the chemical and physico-mechanical properties of concrete/mortar. This study aims to test the properties of high performance mortars containing natural pozzolana. The durability of these materials subjected to various conditions to which the samples were exposed was quantified by the change of strength, density, ultrasonic pulse velocity (UPV) and Vickers hardness. The environmental conditions were as follows: immersion in seawater, saturated sulphate solution (gypsum), running water and cyclical exposure to air/water, to simulate variations in water level. The formation of different crystal phases resulting from the aggressive medium was monitored by X-ray diffraction and scanning electron microscop
Cette publication rapporte l'etude de la durabilite des betons realises avec un ciment CEM I ... more Cette publication rapporte l'etude de la durabilite des betons realises avec un ciment CEM I seul servant de reference, un ciment avec un filler pouzzolanique, un second avec ajout de fillers calcaire et le dernier avec laitier granule. Les milieux de conservation sont : l'eau de mer une, eau seleniteuse et l'eau du robinet servant de reference. Une derniere serie est soumise a des cycles (eau - air) immersion - sechage. L'evolution des phases cristallines est suivie par diffraction X et les mineraux sont observes au MEB; la micro analyse qui lui est associee permet de cerner leur composition chimique. Ces determinations concernent aussi bien les formations superficielles dues aux bains de conservation que les formations internes initiales et leurs evolutions dans le temps.
The search for a quality of concrete is a major concern in Algeria especially after the 2003 eart... more The search for a quality of concrete is a major concern in Algeria especially after the 2003 earthquake (East- Algeria). So it's necessary to improve the properties of concrete using fine particles such as mineral additions as a solution. These are currently used in the concrete to develop its performance and reduce consumption of clinker. This reduction will contribute to economic and easy way to solve problems related to the environment. In this work, an experimental rheological investigation was conducted to evaluate the performances of Algerian metakaolin MK on cement pastes. The latter is obtained from calcined natural kaolin found in large amounts in eastern Algeria (Tamazert- Milia). Several rheological tests were carried out by using the stress controlled rheometer AR2000, on the fresh cement pastes incorporating 0%, 5%, 10%, 15% and 20% of MK. The effects of metakaolin on the rheological behaviour of pastes were discussed. The parameters such as shear stress, viscosity,...
RÉSUMÉ. Cette étude a pour objectif la valorisation de résidus minéraux comme ajout dans les maté... more RÉSUMÉ. Cette étude a pour objectif la valorisation de résidus minéraux comme ajout dans les matériaux de construction à matrice cimentaire. Elle s’inscrit dans une démarche de développement durable. L’utilisation de résidus industriels récupérés et recyclables en remplacement partiel du ciment Portland dans le béton permet de réduire les émissions de gaz à effet de serre (GES) et se traduit par la fabrication d’un béton avec un impact environnemental moindre. En mettant à profit différentes techniques expérimentales, une attention particulière est accordée au comportement de la poudre de marbre finement broyée associée au ciment Portland avec addition de calcaire. Cette étude confirme l’amélioration des propriétés physicochimiques des bétons avec ajout de poudre de marbre, ce qui est de bon augure quant à son utilisation en tant qu’ajout cimentaire.
International audienceA variety of soluted sulphates are often found in groundwater, wastewater o... more International audienceA variety of soluted sulphates are often found in groundwater, wastewater or seawater. These sulphate solutions are aggressive for concrete and react with cement paste hydrates, which can cause expansion and and even loss of the binding properties of C-S-H phase. Two high performance concretes reinforced with steel fibres, produced of Portland cement or of binder in which 15% of cement was replaced by blastfurnace granulated slag, were used in this work. On the basis of flexural and compressive strength, as well as capillary suction, porosity and water absorption measurement of concrete samples cured in saturated gypsum solution it was found that they are resistant in this condition. After 24 months of gypsum solution attack some changes of microstructure were found, which are the beginning of corrosion of concrete without sla
Purpose Around the world, many structures are affected by pathological reactions between the conc... more Purpose Around the world, many structures are affected by pathological reactions between the concrete and the surrounding environment in which these structures are designed, these pathologies lead to compromise their serviceability. In this context, this paper aims to study the durability of concrete in different environments with non-destructive techniques, by studying its contamination by the aggressive agents’ penetration. And this, by evaluation of the influence of the durability indicator that is the absorption by immersion, on the mechanical properties (compressive strength, modulus of elasticity and damage), of specimens having undergone immersion/drying cycles, in different aggressive media (water, seawater and acids: sulfuric and acetic with a concentration of 5%). Design/methodology/approach Concrete specimens were manufactured in the laboratory, and then underwent immersion/drying cycles, in parallel, the weight gain of the specimens was carried out in the wet state after...
3rd INTERNATIONAL SYMPOSIUM ON MATERIALS AND SUSTAINABLE DEVELOPMENT, Nov 7, 2017
International audienceLe matériau béton, demeure depuis son existence au début de XIXème siècle, ... more International audienceLe matériau béton, demeure depuis son existence au début de XIXème siècle, l'élément clé dans le génie civil, et présente toujours une partie intégrante dans la construction en particulier, l'ossature de l'ouvrage. Son emploi large et intensif, soulève le problème de sa qualité et de sa durabilité. A l'heure actuelle, il est possible de fabriquer des bétons plus de 150 MPa à condition de pouvoir se disposer, d'un ciment spécialement conçu à cet effet, des fibres métalliques, des granulats particulièrement performants et d'un superplastifiant qui n'entraîne pas d'air piégé. Notre travail s'inscrit dans le cadre de la valorisation des matériaux locaux, il est basé sur la fabrication d'un BFUHP économique à partir des matériaux existants sur le marché Algérien, ayant des propriétés rhéologiques, mécaniques et de durabilité très élevées. Ce travail sera consacré d'une part à la formulation d'un béton BFUHP à base de matériaux locaux ciment, fibres métalliques et sable et d'autre part à l'étude de l'effet des fibres sur le comportement physico-mécanique du béton. La formulation sera obtenue par la recherche du pourcentage optimal des fibres et en adoptant comme critère la maniabilité du béton. Pour le dosage optimal retenu en fibres, on étudiera l'influence des fibres sur le comportement mécanique du béton résistance à la compression, résistance à la traction et ductilité. Les résultats de cette étude vont mettre en évidence l'impact de la microstructure sur l'amélioration des caractéristiques physico-mécaniques du béton
We found the euryhaline microalga, Tetraselmis jejuensis sp. nov., which was adapted to supralitt... more We found the euryhaline microalga, Tetraselmis jejuensis sp. nov., which was adapted to supralittoral tide pools with salinities varying from 0.3–3.1%. Fifteen strains of T. jejuensis were isolated from Daejeong (DJ) and Yongduam (YO), and clonal cultures were established in the laboratory. Morphological characterization revealed that the cells have a compressed shape, four flagella emerging from a depression near the apex in two opposite pairs, a cup-shaped chloroplast containing one pyrenoid surrounded by starch, and eyespot regions not located near the flagellar base. T. jejuensis cells showed distinct characteristics compared to other Tetraselmis species. First, a regular subunit pattern with honeycomb-like structures was predominantly displayed on the surface in the middle of the cell body. Second, the pyrenoid was invaded by both cytoplasmic channels comprising electron-dense material separated from the cytoplasm, and two branches of small cytoplasmic channels (canaliculi) in ...
L'utilisation de beton a hautes performances (BHP) integrant des ajouts cimentaires comme les... more L'utilisation de beton a hautes performances (BHP) integrant des ajouts cimentaires comme les cendres volantes, les fumees de silice ou le laitier hydraulique cimentaire a augmente considerablement au cours des deux dernieres decennies. Les ouvrages en BHP durent plus longtemps et entrainent des frais d'entretien moins eleves que ceux en beton ordinaire. De plus, le BHP utilise moins de ciment, ce qui diminue les emissions de CO2. Une plus vaste utilisation du beton a hautes performances integrant des ajouts cimentaires pourrait donc entrainer des benefices tant environnementaux que financiers et construire des ouvrages plus durables. A l’etat actuel, la recherche sur les betons a hautes performances en Algerie est surtout axee sur leurs formulations en vue de produire des betons de meilleures resistances et durables. Cependant, une composition optimale depend de plusieurs parametres, en particulier du choix des ingredients. L'effet des ajouts cimentaires et leur finesse...
Journal of Materials and Engineering Structures, 2016
This article is part of a summary of the work developed in conjunction with the Laboratory of Civ... more This article is part of a summary of the work developed in conjunction with the Laboratory of Civil Engineering and Mechanical Engineering from INSA Rennes and Research Unit: Materials, Processes and Environment, University of Boumerdes. One of the objectives was indeed to promote, through studies of variants, the use of local cementitious additions in the formulation of high performance concretes (HPC). The binding contribution of mineral additions to the physical, mechanical and durability of concrete was evaluated by an experimental methodology to subjugate their original granular and pozzolanic effect. The results show that the contribution of couple cement -slag intensification of the matrix is higher than that obtained when the cement is not substituted by addition. Therefore, a significant improvement in performance of concretes was observed, despite the adverse action immersion cycles - drying maintained for 365 days.
Journal of Building Materials and Structures, 2014
Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel... more Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel fibers extends its possibilities. This study was performed to compare the properties of SCC and fiber reinforced self-compacting concrete (FRSCC) with high volume of mineral addition. Six mixtures were elaborated in this study. The content of the cementitious materials and the water/cementitious materials ratio were kept constant, 500 kg/m3 and 0.34 respectively.The self-compacting mixtures have been prepared with a cement replacement of 30% by weight of marble powder. Two different types of steel fibers were used in combination with different lengths (50 mm and 30 mm), keeping the total fiber content constant at 60 kg/m3. Slump flow time and diameter, sieve stability, and L-Box were performed to assess the fresh properties of the SCC and FRSCC. Compressive strength, splitting tensile strength, flexural strength and ultrasonic pulse velocity were determined for the hardened properties. ...
This paper reports an experimental study of the influence of marble powder used as partial substi... more This paper reports an experimental study of the influence of marble powder used as partial substitute for Portland cement (PC) on the mechanical properties and durability of high performance concretes. The analysis of the experimental results on concrete at 15% content of marble powder with a fineness modulus of 11500 cm 2 /g, in a chloride environment, showed that it contributes positively to the perfection of its mechanical characteristics, its durability with respect to migration of chloride ions and oxygen permeability. On the basis of the experiments performed, it can be concluded that the marble powder is suitable for formulation of high performance concretes (HPC) and their properties are significantly better compared to the reference concrete (RC).
American Journal of Civil Engineering and Architecture, Jul 5, 2016
The production of a high performance concrete (HPC) has expanded the scope use of concrete expose... more The production of a high performance concrete (HPC) has expanded the scope use of concrete exposed to aggressive environments, thanks to the limited porosity, the durability, the rheological, physical and mechanical properties with the respect remarkable to a conventional concrete. The objective of this study is to develop a HPC incorporating finely ground limestone. The results show that the substitution of one part of cement by limestone contributes more to the improvement of physical, mechanical and microstructural properties of concrete. The couple cement/limestone contributes significantly to a densification of the matrix unlike when the cement is not substituted by addition. The survey also shows that the limestone does not fall into any chemical reaction. However, the development of resistance (physical phenomenon), obviously depends on the quality of hydrates supplied by the hydration, but also how these hydrates are assembled, their arrangement in space and their connections.
Environnement, Ingénierie & Développement, 2021
The cement industry is a greenhouse gas-generatingactivity since approximately one ton of carbond... more The cement industry is a greenhouse gas-generatingactivity since approximately one ton of carbondioxide (CO2) is emitted into the atmosphere per tonof cement produced. Many mineral products can beadded to concrete to modify their technicalcharacteristics for particular applications and/or toimprove the environmental balance of their lifecycle. This article reports the study of the influenceof the addition of waste marble on the properties ofself-consolidating concrete (SCC). Several additionrates were tested Concrete were prepared with aWater/Binder (W/L) ratio of 0.33 and an equalPortland cement dosage of 400kg/m3. Used alone asa reference composition (white), or with additions ofmarble powder at dosages of 15, 20 and 30% relativeto the mass of the cement. The properties of theself-compacting concrete in the fresh and hardenedstate were tested using specific tests, by varying thefineness of the marble powder at 3000, 7000 and9000 cm2/g and the Superplasticizer content at 1 .5%and 1...
European Journal of Environmental and Civil Engineering, 2014
Most mechanical properties and durability of cementitious materials are related to the performanc... more Most mechanical properties and durability of cementitious materials are related to the performance of the hydrated cement that coats the granular skeleton. In this paper, concrete is formulated by substituting 30% of cement by finely ground glass powder. The experimental study consists of investigating the effect of conservation in tap water or sulphate water on the performance of concrete. The mechanisms of concrete damage have been related to the development of the microstructure of the material. The degradations were observed using scanning electron microscope (SEM) and quantified by X-ray diffraction (XRD). In addition, chloride ions permeability and gas permeability tests were performed. The results showed that glass powder presents a pozzolanic activity and hence it affects favourably the microstructure of the paste which becomes denser and less permeable.
Journal of building materials and structures, Mar 4, 2016
In this work, several reinforced self-compacting concretes were prepared by using three types of ... more In this work, several reinforced self-compacting concretes were prepared by using three types of fibers made of steel, polypropylene and glass, and three different types of mineral additions (marble powder, metakaolin and limestone powder). The water to cement ratio was kept constant at 0.34 and fibers were used in combination, keeping the total fiber content constant at 60 kg/m3. Slump flow diameter, L-Box, stability and air content were performed to assess the fresh properties of the concrete. Compressive strength, flexural strength, splitting tensile strength and ultrasonic pulse velocity of the concrete were determined for the hardened properties. Noteworthy performances were generally obtained, particularly in hardened properties for the self-compacting concretes prepared with steel fibers in association with polypropylene fiber and marble powder as mineral addition.
Certain finely ground mineral admixtures, such as blast furnace slag, pozzolana and limestone, in... more Certain finely ground mineral admixtures, such as blast furnace slag, pozzolana and limestone, influence, to a greater or lesser extent, the chemical and physico-mechanical properties of concrete/mortar. This study aims to test the properties of high performance mortars containing natural pozzolana. The durability of these materials subjected to various conditions to which the samples were exposed was quantified by the change of strength, density, ultrasonic pulse velocity (UPV) and Vickers hardness. The environmental conditions were as follows: immersion in seawater, saturated sulphate solution (gypsum), running water and cyclical exposure to air/water, to simulate variations in water level. The formation of different crystal phases resulting from the aggressive medium was monitored by X-ray diffraction and scanning electron microscop
Cette publication rapporte l'etude de la durabilite des betons realises avec un ciment CEM I ... more Cette publication rapporte l'etude de la durabilite des betons realises avec un ciment CEM I seul servant de reference, un ciment avec un filler pouzzolanique, un second avec ajout de fillers calcaire et le dernier avec laitier granule. Les milieux de conservation sont : l'eau de mer une, eau seleniteuse et l'eau du robinet servant de reference. Une derniere serie est soumise a des cycles (eau - air) immersion - sechage. L'evolution des phases cristallines est suivie par diffraction X et les mineraux sont observes au MEB; la micro analyse qui lui est associee permet de cerner leur composition chimique. Ces determinations concernent aussi bien les formations superficielles dues aux bains de conservation que les formations internes initiales et leurs evolutions dans le temps.
The search for a quality of concrete is a major concern in Algeria especially after the 2003 eart... more The search for a quality of concrete is a major concern in Algeria especially after the 2003 earthquake (East- Algeria). So it's necessary to improve the properties of concrete using fine particles such as mineral additions as a solution. These are currently used in the concrete to develop its performance and reduce consumption of clinker. This reduction will contribute to economic and easy way to solve problems related to the environment. In this work, an experimental rheological investigation was conducted to evaluate the performances of Algerian metakaolin MK on cement pastes. The latter is obtained from calcined natural kaolin found in large amounts in eastern Algeria (Tamazert- Milia). Several rheological tests were carried out by using the stress controlled rheometer AR2000, on the fresh cement pastes incorporating 0%, 5%, 10%, 15% and 20% of MK. The effects of metakaolin on the rheological behaviour of pastes were discussed. The parameters such as shear stress, viscosity,...
RÉSUMÉ. Cette étude a pour objectif la valorisation de résidus minéraux comme ajout dans les maté... more RÉSUMÉ. Cette étude a pour objectif la valorisation de résidus minéraux comme ajout dans les matériaux de construction à matrice cimentaire. Elle s’inscrit dans une démarche de développement durable. L’utilisation de résidus industriels récupérés et recyclables en remplacement partiel du ciment Portland dans le béton permet de réduire les émissions de gaz à effet de serre (GES) et se traduit par la fabrication d’un béton avec un impact environnemental moindre. En mettant à profit différentes techniques expérimentales, une attention particulière est accordée au comportement de la poudre de marbre finement broyée associée au ciment Portland avec addition de calcaire. Cette étude confirme l’amélioration des propriétés physicochimiques des bétons avec ajout de poudre de marbre, ce qui est de bon augure quant à son utilisation en tant qu’ajout cimentaire.
International audienceA variety of soluted sulphates are often found in groundwater, wastewater o... more International audienceA variety of soluted sulphates are often found in groundwater, wastewater or seawater. These sulphate solutions are aggressive for concrete and react with cement paste hydrates, which can cause expansion and and even loss of the binding properties of C-S-H phase. Two high performance concretes reinforced with steel fibres, produced of Portland cement or of binder in which 15% of cement was replaced by blastfurnace granulated slag, were used in this work. On the basis of flexural and compressive strength, as well as capillary suction, porosity and water absorption measurement of concrete samples cured in saturated gypsum solution it was found that they are resistant in this condition. After 24 months of gypsum solution attack some changes of microstructure were found, which are the beginning of corrosion of concrete without sla
Purpose Around the world, many structures are affected by pathological reactions between the conc... more Purpose Around the world, many structures are affected by pathological reactions between the concrete and the surrounding environment in which these structures are designed, these pathologies lead to compromise their serviceability. In this context, this paper aims to study the durability of concrete in different environments with non-destructive techniques, by studying its contamination by the aggressive agents’ penetration. And this, by evaluation of the influence of the durability indicator that is the absorption by immersion, on the mechanical properties (compressive strength, modulus of elasticity and damage), of specimens having undergone immersion/drying cycles, in different aggressive media (water, seawater and acids: sulfuric and acetic with a concentration of 5%). Design/methodology/approach Concrete specimens were manufactured in the laboratory, and then underwent immersion/drying cycles, in parallel, the weight gain of the specimens was carried out in the wet state after...
3rd INTERNATIONAL SYMPOSIUM ON MATERIALS AND SUSTAINABLE DEVELOPMENT, Nov 7, 2017
International audienceLe matériau béton, demeure depuis son existence au début de XIXème siècle, ... more International audienceLe matériau béton, demeure depuis son existence au début de XIXème siècle, l'élément clé dans le génie civil, et présente toujours une partie intégrante dans la construction en particulier, l'ossature de l'ouvrage. Son emploi large et intensif, soulève le problème de sa qualité et de sa durabilité. A l'heure actuelle, il est possible de fabriquer des bétons plus de 150 MPa à condition de pouvoir se disposer, d'un ciment spécialement conçu à cet effet, des fibres métalliques, des granulats particulièrement performants et d'un superplastifiant qui n'entraîne pas d'air piégé. Notre travail s'inscrit dans le cadre de la valorisation des matériaux locaux, il est basé sur la fabrication d'un BFUHP économique à partir des matériaux existants sur le marché Algérien, ayant des propriétés rhéologiques, mécaniques et de durabilité très élevées. Ce travail sera consacré d'une part à la formulation d'un béton BFUHP à base de matériaux locaux ciment, fibres métalliques et sable et d'autre part à l'étude de l'effet des fibres sur le comportement physico-mécanique du béton. La formulation sera obtenue par la recherche du pourcentage optimal des fibres et en adoptant comme critère la maniabilité du béton. Pour le dosage optimal retenu en fibres, on étudiera l'influence des fibres sur le comportement mécanique du béton résistance à la compression, résistance à la traction et ductilité. Les résultats de cette étude vont mettre en évidence l'impact de la microstructure sur l'amélioration des caractéristiques physico-mécaniques du béton
We found the euryhaline microalga, Tetraselmis jejuensis sp. nov., which was adapted to supralitt... more We found the euryhaline microalga, Tetraselmis jejuensis sp. nov., which was adapted to supralittoral tide pools with salinities varying from 0.3–3.1%. Fifteen strains of T. jejuensis were isolated from Daejeong (DJ) and Yongduam (YO), and clonal cultures were established in the laboratory. Morphological characterization revealed that the cells have a compressed shape, four flagella emerging from a depression near the apex in two opposite pairs, a cup-shaped chloroplast containing one pyrenoid surrounded by starch, and eyespot regions not located near the flagellar base. T. jejuensis cells showed distinct characteristics compared to other Tetraselmis species. First, a regular subunit pattern with honeycomb-like structures was predominantly displayed on the surface in the middle of the cell body. Second, the pyrenoid was invaded by both cytoplasmic channels comprising electron-dense material separated from the cytoplasm, and two branches of small cytoplasmic channels (canaliculi) in ...
L'utilisation de beton a hautes performances (BHP) integrant des ajouts cimentaires comme les... more L'utilisation de beton a hautes performances (BHP) integrant des ajouts cimentaires comme les cendres volantes, les fumees de silice ou le laitier hydraulique cimentaire a augmente considerablement au cours des deux dernieres decennies. Les ouvrages en BHP durent plus longtemps et entrainent des frais d'entretien moins eleves que ceux en beton ordinaire. De plus, le BHP utilise moins de ciment, ce qui diminue les emissions de CO2. Une plus vaste utilisation du beton a hautes performances integrant des ajouts cimentaires pourrait donc entrainer des benefices tant environnementaux que financiers et construire des ouvrages plus durables. A l’etat actuel, la recherche sur les betons a hautes performances en Algerie est surtout axee sur leurs formulations en vue de produire des betons de meilleures resistances et durables. Cependant, une composition optimale depend de plusieurs parametres, en particulier du choix des ingredients. L'effet des ajouts cimentaires et leur finesse...
Journal of Materials and Engineering Structures, 2016
This article is part of a summary of the work developed in conjunction with the Laboratory of Civ... more This article is part of a summary of the work developed in conjunction with the Laboratory of Civil Engineering and Mechanical Engineering from INSA Rennes and Research Unit: Materials, Processes and Environment, University of Boumerdes. One of the objectives was indeed to promote, through studies of variants, the use of local cementitious additions in the formulation of high performance concretes (HPC). The binding contribution of mineral additions to the physical, mechanical and durability of concrete was evaluated by an experimental methodology to subjugate their original granular and pozzolanic effect. The results show that the contribution of couple cement -slag intensification of the matrix is higher than that obtained when the cement is not substituted by addition. Therefore, a significant improvement in performance of concretes was observed, despite the adverse action immersion cycles - drying maintained for 365 days.
Journal of Building Materials and Structures, 2014
Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel... more Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel fibers extends its possibilities. This study was performed to compare the properties of SCC and fiber reinforced self-compacting concrete (FRSCC) with high volume of mineral addition. Six mixtures were elaborated in this study. The content of the cementitious materials and the water/cementitious materials ratio were kept constant, 500 kg/m3 and 0.34 respectively.The self-compacting mixtures have been prepared with a cement replacement of 30% by weight of marble powder. Two different types of steel fibers were used in combination with different lengths (50 mm and 30 mm), keeping the total fiber content constant at 60 kg/m3. Slump flow time and diameter, sieve stability, and L-Box were performed to assess the fresh properties of the SCC and FRSCC. Compressive strength, splitting tensile strength, flexural strength and ultrasonic pulse velocity were determined for the hardened properties. ...
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