Mahfoud Benzerzour

Natural Dewatering of Marine Dredged Sediments

The aim of this study is to explore the water content decrease in dredged sediment by natural evaporation and/or drainage. This operation constitutes, in several fields, a preliminary operation to insure a reliable beneficial use of this material. Firstly, a methodology is proposed to assess the relative efficiency of drainage and evaporation in the process of water content reduction in the dredged sediment. Secondly, comparisons of measured evaporation rates are compared to predictions of an available model in the literature. Thirdly, the observed stages during drying are explained in the light of standard parameters measured on the sediment. Finally, a relationship between water content decrease and increase of shear strength of the sediment is discussed. These results will allow a better management of beneficial use of the sediment and enhance scheduling of the drying operation and its transport.

Beneficial reuse of Brest-Harbor (France)-dredged sediment as alternative material in road building: laboratory investigations

ABSTRACT The scarcity of natural aggregates promotes waste reuse as secondary raw material in the field of civil engineering. This article focuses on the beneficial reuse of marine-dredged sediments in road building. Thus, mixtures of raw sediments and dredged sand collected from Brest Harbur (Bretagne, France) were treated with road hydraulic binders. Formulation were prepared and characterized as recommended by the French Technical Guidelines for soil treatment with lime and/or hydraulic binders. Mechanical resistance results are quite similar for both the hydraulic binders, suggesting a similar reactivity with the studied sediment sample. However, some discrepancies can be noted on sustainability parameters. Indeed, water resistance after immersion at 40°C is significantly better for the mixtures treated with cement containing more glass-forming oxides (SiO2 + Al2O3) and fluxing (Fe2O3+CaO + MgO + K2O + Na2O). Moreover, the both hydraulic binders can lead to swelling in the road materials as observed in scanning electron microscopy analyses. Indeed, microscopic observations indicated volumetric swelling of treated samples, which is greatly influenced on the one side by ettringite quantity and on the other hand by the presence of water in pores material.

Experimental Results of Polyester/Glass Fibers – Cementitious Matrix Bond Characteristics: Effect of Silane on Fibers

In this paper, the effect of silane treatment on the bond characteristics of fiber in cementitious matrix, including bond strength and pullout energy are presented. These fibres arise from recycling by crushing of thermoset composite based on unsaturated polyester/glass fiber. Various silane treatment contents ranging from 0% to 1% are used. This treatment by silane enhances the fiber–matrix interfacial properties, especially in fiber pullout energy. However, the bond strength was increased by 150% and the pullout energy was increased by 300%. It is also concluded that in terms of the bond characteristics, the optimal content of silane is 0.5%, given the conditions of the experimental program. The micro structural observation confirms the findings on the interfacial-toughening mechanism drawn from the fiber pullout test results.