Evaluation of the Mechanical and Environmental Properties of Self-Compacting Mortars with Raw Harbour Dredging Sediments (SCMs)

Abstract

The purpose of this study was to evaluate the environmental impact of the use of harbour dredging sediments (HDS) from active lagooning in the formulation of self-compacting concrete (SCC). Concerning the beneficial use of sediments as alternative granular material in construction, the developed experimental methodology allows to incorporate a more optimized content of sediments in cementitious materials than the current experimental approaches. The studied sediments do not undergo any chemical or thermal treatment. The DMDA (Densified Mixture Design Algorithm) method was used to formulate cementitious materials and optimize the sediment content. The paper focused on mortars equivalent to these “sediments” (SCMs). The experimental program considered three different HDS with three different fines rates at 125 μm. Considering the environmental regulation context, the studied HDSs are classified as non-hazardous waste with reference to the European Directive 1999/31/EC—Decision 2003/33/EC. Heavy metals contained in sediments were stabilized with the cementitious matrix, except nickel. In particular, a notable decrease in barium and chloride concentrations was observed. The different mortars are classified as inert, the clinker hydration producing hydrates that capture and stabilize heavy metals in the cementitious matrix. After a 28-day curing period in water at 20 ℃, a C25/30 mechanical class concrete was obtained. The obtained experimental results show that raw HDS from active lagooning has a real potential to be used as a secondary raw material with the incorporated notable quantity in the SCC formulation.