International Journal of Sediment Research, Vol. 29, No. 3, 2014, pp. 391–401 - 391 - International Journal of Sediment Research 29 (2014) 391-401 Characterization of Tunisian marine sediments in Rades and Gabes harbors Imen BEL HADJ ALI 1 , Zoubeir LAFHAJ 2 , Mounir BOUASSIDA 3 , and Imen SAID 4 Abstract The objective of this article is to study the geotechnical and environmental characteristics of sediments dredged from two Tunisian harbors: Rades and Gabes. The first harbor represents the main facility place in the national transport chain. The second one is selected as its sediments present a serious ecological constraint caused by the discharge of wastes into the marine environment. These sediments are either discarded at sea or landfilled despite their harmful effects on the environment. The article is divided into three main sections. The first one presents the material that was carried for Rades and Gabes harbors. The conservation conditions and the used experimental tests are detailed. Geotechnical characterization includes the determination of the grain size distribution, the water content, the Atterberg limits, the methylene blue value, the specific area, the bulk density, the specific unit weight, the organic and carbonate contents. Environmental characterization is assessed by the determination of metals concentrations in a leaching solution. The second section deals with the description and analysis of geotechnical properties of Rades and Gabes harbors’ sediments. The results obtained show that Rades harbor sediments are slightly sandy clayey silts whereas Gabes harbor sediments are silty sands characterized by a highly plastic clay fraction. Both of the two sediments don’t exhibit a high organic content. Finally, chemical, mineralogical and environmental properties are presented and then analysed. The experimental results obtained show that Rades and Gabes sediments could be used as a sand substitute in the formulation of a new construction material. Gabes harbor sediments are more polluted than Rades harbor sediments. Key Words: Sediments, Characterization, Geotechnical, Environmental, Valorization 1 Introduction Channels and harbors must be dredged regularly to ensure the proper functioning of trade by sea. Due to the industrial history of some regions characterized by commercial activities an important part of dredged sediments is actually polluted. Pollution of sediments is mainly linked to organic (PAHs, PCBs, TBT and dioxins) and inorganic (heavy metals: lead, chromium, zinc, copper) pollutants, which may, above specific thresholds, have serious consequences on humans, fauna and flora (Samara et al., 2008). Sea deposit and landfilling were the alternatives to the disposal of the processed material. Since the convention of London in 1972 (IMO, 1972) has been implemented, management of dredged sediments has become an environmental and economic concern for a large number of countries (Marot, 1998). The effect of disposal in open-water has been largely studied (Fettweis et al., 2011; Van der Wal et al., 2011). Landfilling requires large spaces and long-term monitoring; however, it causes a NIMBY reaction. Thus, several researchers and engineers have focused on the development of new solutions for a better environmental management (Gardner et al., 2007). Treatment processes reduce the toxicity and the volume of dredged material, but in comparison with open-water and upland disposal, their costs are not very competitive because of the large volumes of sediments and the heavy pollution (Lafhaj & Husson, 2011). This underlines the necessity to find ecological valorization paths for processed material to make these alternatives economically competitive (Sheehan & Harrington, 2012). Thus, researchers have started to study alternative paths to incorporate large amounts of processed sediments into different aspects of construction and road materials i.e. in clay bricks (Hamer et al., 1999; Hamer & Karius, 2002; Weng et al., 1 Assis., Dr Ecole Centrale de Lille, Villeneuve d’Ascq, France and Ecole Nationale d'Ingénieurs de Tunis, Tunisia, E-mail : belhadjaliimen@gmail.com 2 Prof., Dr Ecole centrale de Lille, Villeneuve d’Ascq, France, E-mail: Zoubeir.Lafhaj@ec-lille.fr 3 Prof., Dr, Université de Tunis El Manar/Ecole Nationale d'Ingénieurs de Tunis/05-UR-11 06, E-mail : mounir.bouassida@enit.rnu.tn 4 Assis. Lecture Dr, Université de Tunis El Manar/Ecole Nationale d'Ingénieurs de Tunis/05-UR-11 06, E-mail : imensaid2@gmail.com Note: The original manuscript of this paper was received in Jul. 2013. The revised version was received in Jun. 2014. Discussion open until Sept. 2015.