Abstract: A method for retarding hydration of a surface of a hydraulic composition includes shaping the hydraulic composition, applying an emulsion onto the surface of the hydraulic composition, and removing a film and a surface layer formed by a non-hardened hydraulic composition from the surface of the hardened hydraulic composition after hardening the hydraulic composition. The emulsion has an oily phase and an aqueous phase, in which the oily phase is dispersed in the aqueous phase. The emulsion includes a non-quaternary amine surfactant and an acid having a set-retarding effect.

Abstract: The invention relates to an emulsion consisting of an oily phase dispersed in an aqueous phase, comprising a non-quaternary amine surfactant and an acid with a set-retarding effect as well as to a method for its preparation. Moreover, it relates to a method for surface retarding of a hydraulic composition, comprising the steps of: (a) shaping the hydraulic composition; (b) applying onto the surface of the hydraulic composition, the emulsion according to the invention, which by breaking releases the oily phase; and (c) after hardening of the hydraulic composition, removing the film formed with the non-hardened hydraulic composition surface layer.