Optimisation D’un Éco-bap À Base De Sédiment De Dragage Vis-à-vis Des États Frais, Durci Et De La Durabilité »

Résumé: According to the specificities related to the formulation of self-placing concretes (SCC) and in particular to their high paste volume content and the presence of large quantities of mineral additives and substitutes, their behavior in the fresh state and the hardened state and their durability are strongly influenced by these two parameters. Treated sediments with pozzolanic properties can be used as additives or partial substitutes for cement, which makes the self-placing concrete technology a good channel for their valorization. This study aims to contribute at the valorization of treated mud from the Chorfa II dam (Algeria) as a partial mineral substitute for CPA CEMI 42.5 cement in the composition of a self-compacting concrete. It is therefore in this study to optimize the percentage of substitution with calcined mud for the development of an eco-SCC showing good technical and economic requirements. Four formulations were retained after the formulation and characterization steps, they cover a single class of resistances and four percentages of substitution, the SCC are: a cementbased control SCC and without any percentage of substitution which we will call the (BAP-T) and 3 SCCs based on 3 percentages of substitution with calcined mud namely: 10, 20 and 30%, their corresponding SCCs are respectively: BAP-V 10%, BAP-V 20% and BAP -V 30%. The SCCs containing calcined mud showed very similar performances to those of the reference SCC (BAP-T) even better for long-term mechanical properties. However, the good mechanical performances are necessary but remain insufficient to be able to qualify a SCC, in fact the durability is a paramount condition for the challenge of valorization, that is why the present paper shows that besides the mechanical resistances, the various SCCs containing calcined mud, were tested for porosity, gas permeability and the diffusion of chlorides. The results showed that the substitution rates of cement by calcined mud up to 30%, affect gas permeability and chloride diffusion but in a satisfactory way, making the SCC of this study potentially durable and resistant to different aggressive media

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