What are materials added to masonry cements for specific purposes called?

The correct term for materials added to masonry cements for specific purposes is "admixtures." Admixtures are substances that are introduced during the mixing process to enhance certain properties of the concrete or mortar, such as workability, durability, setting time, or strength. They can include a wide range of materials, such as water-reducing agents, retarders, accelerators, and plasticizers, each serving a particular function in the final mix.

Understanding the role of admixtures is crucial in masonry and concrete work, as they can significantly affect the performance characteristics of the mortar or concrete beyond what the basic ingredients can achieve on their own. While additives and fillers may be used in construction materials, they do not specifically refer to those materials incorporated into cement mixtures to modify performance characteristics in the same way that admixtures do. Composites, on the other hand, refer to materials made from two or more constituent materials that remain separate and distinct, which is not the focus of this question.