Impact of Heat-Treated Sediments as Cement Replacement on Workability, Strength, Gas Permeability and Chlorides Diffusion of Self-Compacting Concrete

Abstract

Dredging operations produce large quantities of fine dam sediments, which can have a significant impact on the environment. This study aims to contribute at the valorization of treated sediments from the Chorfa II dam (Algeria) as a source of supplementary cementitious material (SCM) in the composition of an ecological self-compacting concrete (SCC). The four SCCs prepared with different rates of cement replacement (0%, 10%, 20% and 30%) using calcined sediment were tested in their fresh and hardened states. However, the good mechanical performances are essential 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 sediments were tested for porosity, gas permeability, chloride diffusion and sulfate attack. The result at fresh state show that the introduction of calcined sediments into SCCs leads to a loss of workability due to its large specific surface area and grain structure, which requires an increase in the dosage of superplasticizer. The SCCs containing calcined sediments showed very similar performances to those of the reference SCC-R even better for long-term mechanical properties. The gas permeability and chloride diffusion values all depend on the rate which cement is replaced by treated sediments. Through the durability test findings, it is noted that calcined sediments performed very similarly to, or even better than, natural pozzolana in terms of the resistance of SCCs to sulfate attack.