MECHANICAL RESISTANCE PERFORMANCE OF CEMENT MORTARS REUSING SEDIMENTS FROM RESERVOIRS IN SOUTHERN ITALY

The focus on circular economy is increasing to achieve sustainable development. This requires decisions to valorise all waste materials that can be reused in different production cycles, rather than disposing as waste. Research has been conducted for a very long-time on dredged sediments all over the world to evaluate their potential for reuse and prevent their landfill disposal. This study investigates the possibility of valorisation of lake sediments in the cementitious materials industry, to make mortars for construction applications. Sediments valorisation makes extraction sustainable and decreases the land consumption required for the procurement of virgin material previously used to make mortars. Sediment samples from two reservoirs (the Camastra and the San Giuliano) in southern Italy were used to make cement matrix specimens. For each lake, different mixes were made by replacing aggregate with varying quantities of sandy sediments from the reservoir. Similarly, samples were made with the addition a of fixed quantity of clayey material by replacing a part of the binder. After 28 days of curing, the bending and compressive strength of the Camastra sediments were lower than those of the San Giuliano sediments, as the Camastra sediment has characteristics more similar to a binder than an aggregate. In the case of Camastra sediments, the mechanical strength obtained by replacing only the aggregate is approximately 25% higher than that obtained by replacing part of the binder. On the other hand, the mechanical strengths of the San Giuliano reservoir sediment are considerably higher as they act as aggregate. This is demonstrated by the fact that mechanical strength is reduced by almost 85% with partial replacement of the binder. As the mechanical strengths of the proposed mortars are lower than those of the normalised mortar, with a more noticeable reduction where even a small amount of binder is replaced with the clay material, the sediments are best suited for reuse in non-structural applications. However, the research is ongoing, to test the idea of using lake sediment to make materials that could perform structural functions.