DREDGED SEDIMENTS AS MATERIALS IN TUNNEL CONSTRUCTION

摘要

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.