Abstract: The invention has for its object: a fabrication process of hydraulic binders, characterized in that it consists:I. in preparing an active product according to a method comprising the following steps:selection of a raw material containing intimately mixed clay phases and calcium carbonate;heat treatment of said material at a temperature between 700 and 900 degrees C.;application during the heat treatment of a partial pressure of carbonic gas opposing the thermal dissociation of the calcium carbonate beyond that which combines with the clay phase;achievement of a simultaneous activation of the clay phases by dehydroxylation (pozzolanic activation) and of the clay-lime combinations with potential hydraulic properties, without formation of free lime;II. in mixing up to 95% of the active product so obtained with the corresponding complement to 100% of an activating product generating calcium hydroxyde.