Effect of Lime and Natural Pozzolana on Dredged Sludge Engineering Properties

 

Walid Zoubir

Geomaterials Laboratory, Civil Engineering Department,
Public Works Ministry of Algeria
e-mail: walidgeo@hotmail.fr

Khelifa Harichane

Geomaterials Laboratory, Civil Engineering Department,
University of Chlef, Algeri
e-mail: kharichane@yahoo.fr

Mohamed Ghrici

Geomaterials Laboratory, Civil Engineering Department,
University of Chlef, Algeria
e-mail: m_ghrici@yahoo.fr

 

 ABSTRACT

All dams in the world are exposed to sedimentation phenomena. This phenomenon has been widely reported in the United States, Russia, Taiwan, Iran, France, Sudan and North Africa. Algeria loses an annual water storage volume of 32 million m3 in the 114 dams in operation; fifteen of these dams are severely threatened by phenomenon of sedimentation. Dredging practices are a challenge for the development and maintenance of dams and ports activities.

In geotechnical engineering, the valorization of dredging sediments and their use in public works is a way increasingly prospected by researchers these last years. Several additives, such as cement, lime and mineral additives such as fly ash, silica fume, rice husk ash…, have been used for stabilization of soft soils. Lime as an additive is most commonly used to stabilize fine soils due to its effectiveness and economic usage. The present study investigates the use of natural pozzolana combined with lime for the stabilization of dredged dam sludge. Laboratory tests were undertaken to study the effect of natural pozzolana, lime or a combination of both on the sludge’s engineering properties. Natural pozzolana and lime were added to sludge at ranges of 0–20 and 0–8%, respectively. Consistency, compaction, unconfined compressive strength tests (UCS) and shear strength were performed on untreated and treated sludge samples to assess the physical and mechanical characteristics of the sludge. Treated samples were cured for 1, 7, 28 and 90 days. The results show that the dredged sludge can be successfully stabilized by combining natural pozzolana and lime.

Keywords: Stabilization, sludge, valorization, lime, natural pozzolana, dredged, compaction, plasticity.

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