Comportement d’un béton à hautes performances à base de laitier en milieu sulfatique

L'utilisation de béton à hautes performances (BHP) intégrant des ajouts cimentaires comme les cendres volantes, les fumées de silice ou le laitier hydraulique cimentaire a augmenté considérablement au cours des deux dernières décennies. Les ouvrages en BHP durent plus longtemps et entraînent des frais d'entretien moins élevés que ceux en béton ordinaire. De plus, le BHP utilise moins de ciment, ce qui diminue les émissions de CO2. Une plus vaste utilisation du béton à hautes performances intégrant des ajouts cimentaires pourrait donc entraîner des bénéfices tant environnementaux que financiers et construire des ouvrages plus durables. A l’état actuel, la recherche sur les bétons à hautes performances en Algérie est surtout axée sur leurs formulations en vue de produire des bétons de meilleures résistances et durables. Cependant, une composition optimale dépend de plusieurs paramètres, en particulier du choix des ingrédients. L'effet des ajouts cimentaires et leur finesse reste peu entrepris. C'est pourquoi nous nous proposons dans ce travail, de formuler des bétons à hautes performances avec et sans ajout cimentaire et de traiter l’influence du laitier de l’usine sidérurgique d’El-hadjar (Algérie), finement broyé et substitué à une partie de ciment, sur les caractéristiques physico-mécaniques des bétons élaborés.Mots clés : BHP - Laitier - Durabilité - Sulphate

The Role of Energy Supply in Economic Growth: Evidence from the Oil Importing Countries

The main purpose of this study is to explore and analyse relationships between energy supply and economic growth. Path analysis and structural equation modelling have been used to analyse the direct and indirect effects of energy supply on economic growth by identifying the form of the relationships between them and the role of mediating variables. Energy supply was found to be strongly correlated with economic growth and to have a number of other relationships and effects on the economy. It was also found that mediating variables had different relationships and effects on the economy based on the source of energy. This result confirms that changes in energy suppliers seem to reflect changes in the political ‎economy of the country rather than shifts in energy use. The influence of the ‎political economy and the preferential treatment of supplying energy to oil importing countries below ‎market price were found to have mixed effects on economic growth for both trade and budget path models.‎ Keywords: Energy supply, Economic growth, Structural equation, Path analysis. ‎ JEL Classifications: Q41, O4, Q43, C32. â€

Effet des déchets de marbre sur la durabilité des bétons en milieu marin

29ème rencontre de l’AUGC Tlemcen (29-31 Mai 2011).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

Influence of marble powder on high performance concrete behavior

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 cm2/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

Influence of Marble Powder on High Performance Concrete Behavior

AbstractThis 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 cm2/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)

Chemical strength of HPC cured in a sulphate environment

A large variety of sulphates, generally coming from underground water or sea waters, can come into contact with the concrete and react chemically with the hydrates, in particular with aluminates, and cause the cracking and the failure of the concrete. The durability of the concretes in a sulphate environment is normally ensured by a sufficient content of cement and the dense structure of the hydrated paste. The combination of natural pozzolans with portland cement makes possible the development of concretes having mechanical properties and a durability much higher than that of a concrete without addition. In order to better determine the pozzolanic effect of the pozzolan addition in the concrete, the evolution of the crystalline phases have been analyzed using x-ray diffraction analysis examined using scanning electron microscopic techniques including the use of chemical analysis to confirm their chemical composition. In parallel with these tests, the evolution of the mechanical bending and compressive strengths have been observed using an automatic test machine. The present study confirms the pozzolanic reactivity of the natural pozzolans use