Abstract: A hydraulic binder including (in % by dry weight); A. at least 50 of at least one ground and granulated blast-furnace slag; B. more than 5 of at least one calcium aluminate cement and/or of at least one calcium sulfoaluminate cement; C. more than 5 of at least one source of sulfate ions; D. between 1 and 5 of Ca(OH)2 and/or Portland cement; E. between 0.01 and 1 of at least one alkali metal carbonate; F. and at least one alkalifying reagent consisting of at least one alkali metal carbonate and/or bicarbonate, different from E; under the following conditions: (i) amount of C allows sulfate ions of C to react with B and A; (ii) the amount of F sufficiently causes a reaction with D in water resulting in a wet formulation with a pH not less than 12, for a water-to-mortar mixing rate between 10 and 35% by weight.