Engineering properties of dredged sediments as a raw resource for fired bricks

Abstract

In the last decades, the amount of dredged sediments (DS) increased in France harbours. Dredged sediments consist of fine soil collected from the deepening, broadening and maintaining of public waterways. The present study reports the investigation of the beneficial reuse of dredged sediments collected from Le Havre (France) harbour as fired material for sustainability requirements. The main challenge is the use of untreated dredged sediments from land deposit of the Seine estuary and port areas as building material, especially for fired bricks manufacture. The chemical, mineralogical and particle size compositions of the raw material were assessed using X-ray fluorescence (XRF), X-ray diffraction (XRD) and laser particle sizer, respectively. The results indicate that the main oxide components are SiO2 and CaO3, while quartz and calcite are the main mineral phases. Lesser amounts of feldspar, chlorite, kaolinite, muscovite and halite were also determined. The physical properties of the raw clay material, including plasticity, organic content and salinity, were investigated in order to assess the product suitability as building material. Ceramic properties such as linear shrinkage, water absorption, bending strength and mineral neo-formations were also investigated in fired bricks at temperatures ranging from 700 to 1000 °C. A high mechanical strength has been obtained at a temperature of 900 °C. The use of ternary diagrams indicates that the raw material falls inside the industrial domain, and ceramic tests show that the raw material could be used in brick making because of its firing behaviour and mechanical resistance. As regards environment sustainability, chemical analysis reveals that the levels of metal traces from leaching tests remain low and within regulatory limits.