On the use of seashells as green solution to mechanically stabilise dredged sediments

The article reports the results of an experimental activity conducted on dredged fine-grained marine sediments and aimed to find out novel eco-friendly solutions for their mechanical stabilisation. The main idea of this research is to use seashells, i.e., another waste material, to partially replace cement binders in the mechanical stabilisation of sediments for the production of a new stable material that can potentially be used in construction. To this aim, an original procedure has been developed to obtain a powder of mussel shells without their calcination. Physical properties, one-dimensional compression behaviour and permeability of the novel mixtures including sediments, mussel shell powder and cements are presented for different curing times. The efficacy of the solutions is assessed also by comparison with the performance of control mixtures prepared by mixing the same sediments with cement only. The effects of the different treatments on the soil properties were analysed, demonstrating multiple beneficial effects of using the mussel shell powder. Evidence is provided that seashells represent a viable alternative to cement, as they were found to be as effective as traditional hydraulic binders, when replacing them up to ¼, in enhance geomechanical and geochemical performance of the stabilised material.