Sustainable Valorization of Dredged Sediments from Mehdia Harbor, Morocco, in Mortar Formulations

The sustainable management of dredged sediments poses a major environmental and economic challenge, particularly in Morocco, where large quantities are annually discarded as waste. Contributing to resource efficiency and circular economy objectives, this study represents the first systematic application research of Moroccan Mehdia Harbor sediments in mortar formulations. Three substitution strategies were investigated at substitution rates of 5–30%: (i) replacement of cement with fine sediments (series MA); (ii) replacement of sand with intermediate sediments (series MB); (iii) replacement of sand with sandy sediments (series MC). Mechanical testing at 28 days showed that both compressive and flexural strengths remained comparable to the reference mortar for substitution levels up to 10–15%, depending on sediment type. Beyond these limits, a marked strength reduction was observed, particularly for cement replacement with fine, clay-rich sediments. Mortars incorporating sandy sediments (MC) exhibited the best performance, maintaining over 80% of the reference compressive strength up to 15%. Leaching tests confirmed the environmental stability of all formulations, which remained within the “inert” waste classification up to 15% substitution. These findings demonstrate that dredged sediment incorporation in mortar is both technically and environmentally feasible for non-structural applications, promoting sustainable materials within a circular economy framework.