Potential Application of Marble and Crushed Mussel Shells By-products to be Used as Aggregates in Plain Concrete Mixes

The main objective of the following paper is to verify the possible applications of marble by-products obtained from the ornamental stone industry and mussel shells deriving from aquaculture farming to be used as alternative aggregates in plain concrete mixes. Both marble and mussel shells came from Sardinia Island (Italy), very active in the commercialization of marble for ornamental purposes and mussels from aquaculture farming. Italy is the third producer in Europe of mussel and one of the leaders worldwide together with China and Turkey for the production of marble. Marble by-products were used to replace coarse natural aggregates while the crushed mussel shells partially replaced fine aggregates. The mixes were studied to obtain non-structural concrete. Various mix designs were studied, in which marble and mussel shells, in different percentages, replaced natural aggregates (sand and gravel). The research aimed to identify the characteristics of the materials through laboratory tests and to create the optimal mix design. From the test conducted it was possible to evaluate that marble and mussel shells by-products can be considered valid alternatives to natural aggregates. From the preliminary results, encouraging mechanical performances were obtained when replacing 50% of coarse aggregates fraction 8–16 mm with marble by-products and 8% of fine aggregates 0–4 mm with crushed mussels shells. The reuse of these materials is essential in a sustainable and environmentally friendly circular economy approach, which focuses on reducing waste and reusing materials within production cycles. The resulting advantages are less exploitation of natural aggregates and less production of waste.