Investigation of Dredged Sediments Reuse as Building Materials

In order to maintain a required water depth and to allow waterways navigable, dredging operations are of a great importance. So, large volumes of sediments are annually dredged in the ports over the world. In Le Havre harbor the annual dredged volume of sediments is close to 1.5 Mm³, which are mainly dumped at sea. Because of its perpetual availability and mineralogical characteristics, the sediment is regarded as a suitable raw material for terracotta production. The aim of this work, assessed in laboratory, is to investigate how dredged and deposited sediments from the Seine estuary and port basins can be used as alternative raw material for the heavy clay industry. The chemical and mineralogical composition of dredged sediments were addressed using X-ray fluorescence (XRF) and X-ray diffraction (XRD), respectively. The physical properties, including plasticity index (PI), organic content, and salinity were investigated. The results from all tested sediments in their raw state showed that their chemical and mineralogical compositions are fairly close. However, their low clay minerals content (6.6%) and their high carbonate content (25.2%) constitute a limitation to their use in ceramic industry. The grain size distribution was appraised on a diagram involving three range sizes (clay, silt, sand), and the results indicated that the raw material falls inside the suitable domain of fired-clay products. Additional ceramic tests performed showed that the raw material can be used as bricks making owing to provided interesting properties, such as firing behavior and mechanical resistance. Leaching test was performed on fired bricks in order to assess the environmental suitability of the construction material. In this framework, The SEDIBRIC project is part of the concern of the “sober management of resources” and aims a sustainable remediation with a low impact on the environment and recovery of dredged sediments.