A hydraulic binder which includes a clinker with a specific shape, the clinker including as main phases, given as weight percentages relative to the total weight of the clinker: (i) 70 to 95% of a belite phase having a particle size such that the Dv50 ranges from 5 to 15 μm; (ii) 5 to 30% of a calcium aluminoferrite phase; and (iii) less than 5% of minor phases; the clinker having an Al2O3/Fe2O3 weight ratio of less than 1.5; and the clinker including less than 5% of alite phase and less than 5% of calcium sulphoaluminate phase; and at least 0.5% dry weight of an activator made of calcium sulphate, as a weight percentage relative to the total weight of phases (i) to (iii).