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Many geotechnical problems involve pavements in Algerian arid regions; the main among them being related to the scarcity of standard materials. Recently, numerous studies were carried out on the va...

In Algeria, the construction of landfill has increased in recent years because of the growth of wastes of all kinds. To realize passive containment barriers during the construction of these centers, a study was conducted on the natural dredged sediments of the Bouhanifia dam (western Algeria), from the settling ponds during their storage. These sediments were treated at different percentages of bentonite (2, 4, 6, 8 and 10%). For each percentage, 2 samples were tested. A series of experimental laboratory tests were conducted to investigate the effect of bentonite content on the geotechnical and hydraulic characteristics of the sediments. The study was carried out on samples compacted under Modified Optimum Proctor (MOP) conditions, MOP ± 3% with water and landfill leachate. The results show that the compaction characteristics were affected by the addition of bentonite, the optimum water content increased and the maximum dry unit weight decreased in the presence of a large amount of bentonite. Atterberg limits increased, and permeability, measured by Falling-Head and Oedometer tests, decreased with treatment, suggesting that bentonite-treated sediments can be used as passive clay barriers for a landfill of hazardous waste.

The main objective of this study is to enhance the performances of local materials in order to be used in road construction sector. To enhance the performances of this local materials, the strategy adopted is to combine the beneficial effects of mixing different materials and treatment using binders. The materials used in this study are tuffs and dune sands. Hence the present work is also a contribution to the co-valorisation of local materials in arid region of the south of Algeria. According to the results obtained, it is shown that the tuffs of the Saharan regions are suitable for the use of Saharan pavements, particularly in base layers and foundations. The incorporation of dune sand up to 20% improves the mechanical performance. The binders treatment (cement, lime and cement/lime) have induced a further improvement in bearing capacity and compressive strength as well as tensile strength. With these improvement, the materials could be used in roads with heavy and important traffic. © 2019, Springer Nature Switzerland AG.

The swelling phenomenon causes various damages and disorders in several regions around the world. Several solutions have been proposed to face such a problem. Among others, one can cite chemical stabilization, mechanical stabilization and physical stabilization. The present work deals with stabilization of swelling Bentonite clay issued from Maghnia (North West of Algeria). First, the material of interest has been characterized based on standard geotechnical tests, direct measurements of free swells and swelling pressure. The influence of lime, cement, lime + cement and lime + salt (NaCl) on the consistency of Bentonite and the parameters of swelling has been addressed. The shear strength and the compressibility of some samples have been investigated. It is found that the plasticity index PI and the swelling parameters are all reduced but with different degrees. The compression index and the swell index are decreased respectively slightly and drastically. The combination lime + salt is shown to be very efficient and of low cost.

Dredged 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.

The economic activity of many ports in Algeria is hampered by the natural phenomenon of sediment accumulation. Dredging is a necessity; however, the storage of the dredged sediments (DS) is a problem for harbour managers. The easy and low-cost solution of dumping sediments at sea raises environmental concerns that could eventually be alleviated by considering these sediments as a new source of construction materials. This would contribute to the reduction of marine pollution and thus give harbour managers the opportunity to be part of the sustainable development approach. This paper examines the feasibility of using DS from the Port of Oran as partial replacement of sand in mortars. The physical, chemical and mineralogical properties of DS were determined after a zoning study was made. DS were treated in order to reduce their salt and water contents so that they could be used as a partial substitution of the sand in the composition of the mortars. The mechanical and durability properties of mortars fabricated by substituting 10, 15 and 20 % of sand mass by DS were determined and compared to those of the reference mortar. The compressive strengths of a first set of mortar specimens were determined after 7, 28, 60 and 90 days of moist curing. The second set of mortar specimens that were submitted to chemical attacks and their residual compressive strengths at 118 days were determined. So far, the preliminary laboratory tests show that partial replacement of 20 % of sand by DS in mortars gives good results.

Resume : L’entretien des fonds de la retenue du barrage de Bouhanifia par le dragage est une solution pour lutter contre l’envasement. Mais ces operations de curage generent de grandes quantites de sediments qui representent un probleme environnemental majeur. Dans ce travail, nous examinons la faisabilite de remplacer une partie du ciment par des sediments de dragage (SD) dans des mortiers. Le comportement rheologique des mortiers et leur resistance a la compression aux echeances de 2, 7, 28, 60 et 90jours, ont ete etudies pour des substitutions de 10% et 15% de ciment par des SD. Les resultats ont montre que la demande en eau pour les mortiers avec SD est plus grande que celle du mortier de reference sans SD. Du point de vue de la resistance a la compression, les mortiers avec SD presentent des resistances similaires a celles du mortier de reference. Mots-cles : Barrage de Bouhanifia, Sediments fluviaux, Dragage, Caracterisation, Substitution du ciment.

Resume : Le devenir des matieres extraites lors des dragages des ouvrages envases (ports, barrages, chenaux, ...) a fait l’objet de nombreuses recherches, mais les applications concretes des resultats restent encore timides. Notre prise en charge des sediments extraits lors des dragages s’est concretisee par l’utilisation de ces materiaux en tant que matieres premieres dans des procedes de confection de materiaux de construction. Quelques pistes de recherche ont ete developpees plus ou moins largement, et pour certaines d’entre elles, ont ete initiees il y a plusieurs annees au sein du LabMat de l’ENPOran. Nous allons les passer en revue, et donner quelques exemples d’etudes et d’applications recentes. Nous presentons l’essentiel a la comprehension de procedes de valorisation des fractions fines solides issues de dragages, en particulier : ‐ Pouzzolanicite de sediments calcines. ‐ Brique a base de sediment de barrage. ‐ Mortier de reparation a base de sediment. ‐ Beton autoplacant a base de vase de barrage. ‐ Corrosion des armatures du Beton arme a base de ciment de vase calcinee. Cette revue n’est pas exhaustive. Cependant, nous esperons montrer toute l’importance que peuvent avoir les travaux de recherche, en laboratoire pour des applications en industrie, en respectant les exigences environnementales d’une part, et en tenant compte des realites economiques locales d’autre part. Mots cles : Dragage, Sediment, Eco-materiau, Valorisation, Pouzzolane, Ciment.

In semi-arid weather countries, the public works as dams are silted in a short time. Our study contributes to make the life work of a dam longer. Our idea is to develop a process using the material extracted by dredging, as first matter to product hydraulic cement. The various physical, chemical and mineralogical analyses carried out on the silt samples showed mineralogical structures allowing several routes of development. We are interested in the very fine solid particles carried by erosion and deposited downstream of the dam. This material has caused many environmental problems after it’s extracted of. In fact, the crystalline structure of the amorphous clay fraction of this silt reacts with water in the presence of lime, as hydraulic cement. Experimentally, silt samples were calcimined at a temperature less than 800 °C, and an amorphous structure appeared. The desired pozzolanic character was therefore confirmed.

The actual shortage of land aggregates and environmental concerns raised by dumping at sea of dredged sediments (DS), more than ever, DS could constitute a new source of building materials. This experimental study investigates the potential of using DS from harbour of Oran in tunnel construction; the first objective is to determine their chemical, physical and mineralogical characteristics. The concept of enhancing building material characteristics based on the component characteristics of DS is considered. Thus, the treatment by the leaching and the natural decantation is used to decrease their salt and water content. Finally, the influence of various percentages of DS (from 20%, to up to 35% of sand mass by DS) in the mechanical behaviour of mortars was analyzed. Compressive strengths of a first set of mortar specimens were determined after 7, 28, 60 and 90 days of moist curing. The second set of mortar specimens, that were submitted to chemical attacks and elevated temperatures, had their residual compressive strengths determined at 118 days and 150 days. So far, laboratory results show that partial replacement of 20% or 25% of sand by DS in mortars give good results.Copyright © 2013 by ASME

Resume : Le travail presente est realise dans le but d’integrer la gestion des sediments de dragage dans une demarche de developpement durable. L’objectif de ce travail est d’utiliser les sediments de dragage du port d’Oran comme composant de substitution dans la confection de materiaux de construction et plus precisement dans les mortiers. L’etude a consiste a elaborer des mortiers en substituant des fractions de sable de 10%, 15% et 20%, par des sediments de dragage. Les resistances mecaniques et aux attaques chimiques (durabilite) ont ete determinees et comparees a celles d’un mortier temoin. Les resultats obtenus en laboratoire ouvrent des perspectives de valorisation des sediments de dragage venant en substitution du sable dans la composition des mortiers. Mots-cles : Valorisation – Mortier – Sediments marins – Resistance a la compression – Durabilite – Substitution – Sable

1. Laboratoire de Materiaux "LABMAT", Ecole Normale Superieure d’Enseignement Technologique d’Oran, BP 1523 Oran El M’naouer, Algerie. asemcha@yahoo.fr Resume : Au port d’Oran, la necessite de maintenir les profondeurs des voies de navigation et d’accostage des cargos demande un curage regulier des bassins. Des reperes historiques traduisent parfaitement les rapports entretenus entre la ville d’Oran et son port. Aujourd’hui, comme dans le passe, la ville doit l’essentiel de sa prosperite a son port et a l’ambition de le faire acceder au rang de grand port mediterraneen, vu qu’il s’agit du premier relais portuaire en eaux profondes depuis Gibraltar, sur la rive sud de la mediterranee. En effet, c’est la situation geographique de la baie d’Oran qui a ete a l’origine de la construction d’un port et de l’urbanisation de la ville d’Oran. De nombreux cours d’eau, aujourd’hui immerges continuent a charrier des sediments qui se deposent au gre des courants dans les fonds des bassins. Un dragage perpetuel est necessaire: ce qui genere des quantites considerables de dechets solides, qui sont contamines dans la plus part des cas. La solution adoptee jusqu’ici qui est basee sur une etude de faisabilite grossiere, est le largage des matieres solides issues des dragages a quelques miles au large des cotes. Notre interet a ete de nous occuper du devenir de ces materiaux en recherchant des voies de leur reutilisation dans le BTP, comme voie alternative a leur simple largage en mer. Bien que le comportement des sediments vis-avis du transfert des polluants soit mal connu, la legislation est de plus en plus sensible a la protection de l’environnement et la preservation des habitats aquatiques menaces. La valorisation des deblais de dragage est recherchee aussi pour amortir les couts lies aux dragages. Apres l’identification des caracteristiques physiques et mineralogiques sur des echantillons preleves lors du dragage du bassin de Mostaganem du port d’Oran, les sediments ont ete traites soit par ajout de ciment soit par traitement thermique. Ces traitements ont permis l’amelioration de leurs caracteristiques mecaniques et ont abouti a des applications concretes en technique routiere ainsi qu’en substitution a une fraction de ciment dans la conception d’un ciment compose. Mots cles : Port d’Oran – Sediment – Dragage – Valorisation – Technique routiere – Ciment

Resume : Le phenomene d’envasement s’est amplifie ces dernieres annees pour le port d’Oran qui a perdu en moyenne un a deux metres de profondeur. Le dragage est alors devenu une necessite vitale. Ce travail s’inscrit dans une approche de continuite avec une etude realisee en 2010, il a pour objectif de determiner le pourcentage le plus efficace de sediments traites (Sediments phosphates et calcines : SPC) a utiliser en substitution du ciment dans les mortiers. A cet effet nous avons confectionne des mortiers avec differents pourcentages de sediments (5%, 10%, 15% et 20%). Les resistances mecaniques et aux attaques chimiques (durabilite) ont ete determinees et comparees a celles d’un mortier temoin. Les resultats montrent que l’ajout de 5% et 10% de sediments traites dans les mortiers a permis d’approcher la resistance mecanique du mortier temoin et d’ameliorer leurs resistances aux attaques chimiques. Mots cles : Sediments de dragage – Ajout – Mortier – Resistance mecanique – Durabilite

Resume : L’etude presentee porte sur la caracterisation de la resistance au cisaillement des sediments d’envasement de la retenue du barrage de Fergoug situe au nord ouest de l’Algerie. En premier, la quantification des apports solides sous forme d’erosion specifique est presentee par une analyse probabiliste. Ensuite, a partir de sondages realises le long des principaux affluents et au pied du barrage, des carottes ont ete prelevees. Dans le but de localiser les zones a cibler pour le dragage, la connaissance de la variation de la resistance au cisaillement est necessaire. A partir des valeurs obtenues sur des echantillons selectionnes, nous presentons dans une seconde etape la cohesion non drainee au niveau de chaque sondage et pour des tranches de profondeurs choisies.