Abstract: A process for constructing infrastructures, in which aggregates, vitrified blast-furnace slag, a pulverulent activator and water are mixed together, the mix is spread out over the ground, compacted and left to harden, and in which a particulate slag and a ready-prepared additive containing, on the one hand, the activator and, on the other hand, dry ground vitrified slag having a particle size of less than 500 &mgr;m are added to the aggregate is provided. Further provided is the additive for the construction of infrastructures according to the said process, which additive includes, on the one hand, a pulverulent activator and, on the other hand, dry ground vitrified slag having a particle size of less than 500 &mgr;m.

Abstract: The present invention relates to a process for manufacturing a soil treatment composition, to soil treatment compositions and to the use of such compositions. The process according to the invention comprises a step of selecting one or more slags having a predetermined free lime content of greater than or equal to a first threshold value, a step (B1) of adding free lime to the slag or slags and a step of grinding the slag or slags in order to obtain a soil treatment composition having a predetermined free lime content of greater than or equal to a second value.