The present invention provides a powder mixture suitable for hydrophobizing and thickening cementitious mortars, comprising a) 5-90 wt % of one or more water-thickeners i), said thickener i) being in powder form and selected from a specific group, b) 5-90 wt % of one or more component ii), wherein component ii) is in powder form and comprises one or more components iia) selected from the group of fatty acids, fatty acid salts, fatty acid derivatives, alkyltrialkoxysilane and/or a dialkyldialkoxysilane, wherein the alkyl group being a C6- to C12- alkyl group and the alkoxy group being a methoxy, ethoxy, propoxy and/or a butoxy group, optionally one or more components iib) selected from the group of water-insoluble polymer, water-soluble polymer, carrier and filler, and optionally one or more components iic), and c) 0-70 wt % of adjuvants iii), said adjuvant iii) being in powder form, wherein thickener i), component ii) and adjuvants iii) are different powders and the added components sum up to 100 wt %, based on the total amount of the powder mixture. The invention further provides a process to make a dry mortar comprising a hydraulic and/or latent hydraulic setting binder and the powder mixture according to the invention, wherein the mixture is made first, followed by mixing it with the binder. The powder mixture and the process provide an easy quality control means to ensure the presence of the component in the dry mortar.