Abstract EN:

The management of dredged sediments is a challenge for our society because of their huge volume. The contamination of heavy metals and organic micro pollutants make that the majority of dredged sediments are regarded as dangerous waste and are put in discharge. This isn't in the same point of view of the durable development policy: the French law supports the valorization so that only ultimate waste is put in discharge. In this context, Solvay Company has developed the process NOVOSOL(r) for the treatment of the dredged sediments polluted. The process comprises two stages: an immobilization of heavy metals by formation of apatite under a phosphatising reaction with acid phosphoric and a destruction of the organic matter by a calcination. The goal of this thesis is to use river sediments treated by the process NOVOSOL(r) in road base materials. Experimental studies in laboratory comprise two aspects: mechanical performance and leaching behaviour. The treated sediments by NOVOSOL(r) are introduced into road base mixes treated with cementitious binders as substitute for regular sand. The preparation of materials according to the normalized methodology in laboratory does not present any difficulty. As the treated sediments content increases, the water demand increases and the materials are less compact than reference material. This is due to the characteristics of treated sediments: important ratio of fines, friability and the porosity of granular. These characteristics have as a consequence to weaken the granular skeleton, which results in a reduction in the stiffness module of materials. On the other side, the reactivity of treated sediments NOVOSOL(r) in the matrix of cimentitious binder and a better homogeneity of materials lead to an improvement of the tensile strength. Mechanical performance of all the materials with of treated sediments NOVOSOL(r) evaluated by index of elastic quality is better than that of the reference material. . .