Hydraulic binder comprising a ternary acceleration system and mortars and concretes comprising one such binder

A mortar or concrete comprising aggregates and a hydraulic binder, the hydraulic binder based on slag cement, the slag cement comprising 20 to 80 weight % relative to a total weight of slag cement, of a blast furnace slag or a mixture of blast furnace slags, the hydraulic binder comprising at least one acceleration additive that is a ternary system comprising:

• at least one alkali metal hydroxide in an amount such that, during mixing with water of the hydraulic binder, a molar concentration of alkali metal hydroxide in the water is from 0.05N to 0.60N, the at least one alkali metal hydroxide being selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide and mixtures thereof;
• at least one alkali metal sulfate at a rate of from 0.2 to 3 weight % of the slag cement;
• and
• at least one source of calcium sulfate in such a proportion that the content of calcium sulfate (CaSO4), relative to the weight of the slag cement, is from 2 to 7%,
• wherein the hydraulic binder presents a mechanical strength to compression after 2 days of at least 8 MPa.

A process of making a hydraulic binder based on slag cement comprising 20 to 80 weight % relative to a total weight of slag cement, of a blast furnace slag or a mixture of blast furnace slags, the complement being clinker, and having a mechanical compressive strength after 2 days of at least 8 MPa, the process comprising adding to the slag cement or forming within the slag cement at least one acceleration additive that is a ternary system comprising:

• at least one alkali metal hydroxide in an amount such that, during mixing in water of the hydraulic binder, a molar concentration of the at least one alkali metal hydroxide in the water is from 0.05 N to 0.60N, the at least one alkali metal hydroxide being selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide and mixtures thereof;
• at least one alkali metal sulfate at a rate of from 0.2 to 3 weight % of the slag cement;
• and
• at least one source of calcium sulfate in proportions such that the level of calcium sulfate (CaSO4), relative to the weight of the slag cement, is from 2 to 7%.