The invention concerns a PROCESS for the preparation of cement / mortar / concrete (for simplicity: "cement") compositions or systems, (hereafter "cement" compositions or systems for simplicity), of a general known type, in which the filler(s) is/are comprising or consist of "calcium carbonate - based filler(s)" , comprising at least one step where the said filler(s) is / are treated with an efficient treating amount of at least one treating agent consisting of or comprising superplastifier(s). The main purpose of this invention is to build a process aimed at providing improved, "High performance", FLUID, cement or mortars or concrete systems or compositions having an improved compacity, an improved flowability, and globally speaking a definitely improved "workability", and "regularity" of the properties of the final systems. The present invention also concerns a filler for "cement" compositions, characterized in that if consists of, or comprises, a calcium-carbonate-based filler or blends of same, pre-treated with an "efficient amount" of at least one superplastifier.