Reuse of Lake Sediments in Sustainable Mortar

The study analyses the possible valorisation of lake sediments for sustainable mortar, in accordance with the principles of the circular economy, to obtain a sustainable material, since reuse occurs without any kind of preliminary treatment and preserves the consumption of virgin raw materials in the mix design. Moreover, it reduces the amount of water to be used in the mix since part of it is already contained in the sediments. The research was performed on sediments dredged from two artificial reservoirs, Camastra and San Giuliano, located in Basilicata, a region in southern Italy. Cement mortar was prepared by completely replacing, at different quantities, the fine aggregate and, for some of it, partially replacing, at a constant quantity, part of the binder. Workability, mechanical strength, and density were measured, as well as the possible release of contaminants. The investigations made it possible to assess the influence of replacing aggregate with sediment on mortar performance, showing that San Giuliano sediment produces mortar with great workability (similar to 140%), comparable to that of normalised mortar. Similarly, the mechanical strengths of some specimens (SG_s1 and SG_s2) were approximately 60 MPa and 52 MPa, respectively (about 15% higher than that of normalised mortar). On the contrary, for the mortar prepared with the Camastra sediments, both workability and mechanical strength were similar to 50% lower than normalised mortar. Furthermore, the leaching test did not reveal contaminant release.