The present invention provides a versatile additive for improving the properties of a cement slurry made with portland cement and to be utilized in well cementing, said versatile additive comprising type of silicates and/or borates that inhibit gelation occurring with the interstitial phase. The additive of the present invention improves significantly the rheology (i.e., strong dispersing effect) and can even overcome severe gelation problems. At temperature above about 88° C. (190° F.) the additive acts as retarder aid, enabling to reduce considerably the concentration of retarder required to achieve a given thickening time.