Slag-based hydraulic binder, dry mortar composition comprising same and system for activating a slag-based binder

A hydraulic binder comprising, 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. between 6 and 30 of at least one source of sulfate ions selected from the group consisting of natural or synthetic gypsum, calcium sulfate hemihydrate, bassanite, anhydrite, selenite, alabaster, fibrous gypsum, saccharoidal gypsum, marine gypsum, gypsum flower, phosphogypsum, desulfurization gypsum, titanogypsum, citrogypsum, tartarogypsum, borogypsum, lactogypsum and mixtures thereof;
• D. between 1 and 5 of Ca(OH)2 and/or of 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;
• subject to the following conditions:
• (i) an amount of C is sufficient to allow the sulfate ions of C to react with B and with A;
• (ii) the amount of F is sufficient so that its reaction with component D in a presence of water brings the pH of a resulting wet formulation to a value of not less than 12, for a water-to-binder mixing rate of between 10 and 35% by weight,
• wherein 1≤[C]/[B]≤3;
• and
• wherein the hydraulic binder is free from any polyvinyl alcohol.