Water-repellent admixtures for cementitious materials

The present disclosure provides improved water-repellent admixtures for cementitious materials. The water-repellent admixtures are incorporated during masonry processing to improve the water resistance of the final product. Solid water-repellent admixtures may be conveniently incorporated into pre-blended dry mortar mixes. In some variations, a pre-blended dry mortar mix comprises a cementitious material, an aggregate, and a dry water-repellent admixture, wherein the water-repellent admixture contains one or more materials selected from the group consisting of silanes, siloxanes, free fatty acids, fatty acid derivatives, particulated polymers, and particulated copolymers, and wherein the water-repellent admixture is present in the pre-blended dry mortar mix in a dosage from about 0.01% to about 1.00% by weight of the pre-blended dry mortar mix. Water repellency is achieved while maintaining workability as well as the properties of the hardened mortar, including compressive strength and bond strength to other substrates, such as clay or concrete masonry units.