Influence des additions minérales sur la résistance mécanique des mortiers

Les grands ouvrages tels que les tunnels sont de gros consommateurs du matériau béton dans lequel des millions de tonnes de ciment sont utilisés pour leur réalisation. La fabrication du ciment ternaire en utilisantdes additions minérales (Fines Siliceuses : FS) représente double intérêt lorsque le ciment Portland n’est pas largement disponible ; d’une part cela permet de diminuer les émissions de CO2 et d’autre part d’obtenir unliant moins coûteux. Cet article présente les résultats des résistances à la compression du mortier contenant différents pourcentages de FS. Le ciment a été partiellement remplacé par 0, 5, 10, 15 et 20 % de FS. Aussinous avons utilisé les dosages recommandés par le fabricant à savoir 15 et 30 Kg/m3. Le rapport liant -sable et liant - eau ont été maintenu respectivement constant à des valeurs 1/3 et 0,52. Les échantillonsont été mis à la cure dans l’eau jusqu’aux échéances de l’écrasement. Des essais de résistance à la compression ont été effectués à différentes échéances 7, 28, 60 et 90 jours. Un mortier témoin (CPA + 15 % de pouzzolane naturelle) a été confectionné pour les besoins de comparaison.Mots-clés : grands ouvrages-tunnels, ciment ternaire, addition minérale, mortier, résistance mécanique

Genetic programming for brick's chemical analysis modelling

This study is part of the search for a sediment management methodology and the basic material that is designed for the manufacture of fired brick, in which we tackle the problem of choosing the mud samples from dredging the Algerian dams in particular (Bouhanifia dam western Algeria) and the choice of clay that comes from different deposits. We propose an approach for sampling using a computer optimization model that allows solving and optimizing a characterization to retain the best adapted sample (chemically) using the genetic algorithm.Keywords: Sludge- Dredging- Sample- Chemical Characterization- Brick-Optimization Methods- Genetic Algorithm

The effect of high temperatures on concrete incorporating ultrafine silica and polypropylene fibers

In recent years, lots of studies have attempted to examine the possible causes for the thermal instability of ordinary concrete and high performance. However, we still do not know the exact terms of phenomena taking place during exposure to high temperature and the technological solutions that exist (polypropylene fibres, thermal reported) are not always well controlled.In this work, several concrete formulations have been tested and multi-scale observation of high-temperature behavior of ordinary concrete (compressive strength of 48 MPa) and HPC (compressive strength 75 MPa) were adopted. On the scale of the material, the identification of trends with temperature data such as porosity and particularly the mechanical properties allow us to better understand the behaviour of concrete at high temperature differential thermal analysis have been also made.</p

Characterization and valorisation of sludge of wastewater treatment plant (WWTPs) into cement industry

International audienceIn Municipal sewer sludge production in EU is expected to rise to 13.0 million tons in 2020. Also in Algeria the estimated quantity of sludge produced in 2017 will exceed 2.0 million tons per year. Since there production, the treatment and disposal of sewage sludge is become an economically and environmentally sensitive problem. The challenge facing sludge managers is to find cost-effective and innovative solutions whilst responding to environmental, regulatory and public pressures. Methods were developed for reducing and disposal the quantities of generated sludge. The present paper is a contribution to valorizing the ashes sludge of wastewater treatment plants (WWTPs) for the production of a green-cement. Mineralogical and physic-chemical characterizations of ashes sludge were carried out. Ashes contain significant amounts of Al2O3 and SiO2 and can be used as a partial replacement of clinker. Four green-cement samples were prepared by substitute (5, 10, 15 and 20%) of ashes into cement standard. Mechanical tests (compressive strength and bending tensile strength) were carried out to the sample mortars (40x40x160mm3) made of green-cements at different curing times (2, 7 and 28 days). The results show that after 28 days of curing, the compressive strength exceeds 50 MPa. The same trend is observed with specimens tested in bending tensile strength exceeding 7 MPa. These results are encouraging for better management of sludge from Algerian plants in the field of cement industry. © 2017, University of Mohammed Premier Oujda Morocco

Durability of Mortars Made with Dredged Sediments

AbstractDredged sediments cause serious problems for harbour managers of Oran due to lack of storage areas on land, then the solution chosen is a dumping at sea. The present study is based on the physical and chemical analysis of sediments collected from different docks of the port of Oran. Results obtained have allowed delineating areas of contamination. Contaminated sediments are dangerous wastes. Those contaminated by organic and inorganic pollutants are submitted to the natural treatment (leaching and dewatering) and to the chemical treatment with phosphate for their reuse as construction materials in civil engineering as mortars.The results of tests mortars resistance and durability led to the conclusion of the technical feasibility of this solution