Aggregate refers to the granular material—such as sand, gravel, crushed stone, and recycled concrete—used in conjunction with a cementitious medium to form concrete or mortar. Aggregate typically makes up about 60–80% of the concrete mix, and its properties significantly influence the concrete’s strength, durability, and other performance characteristics. The selection of aggregate is based on factors such as size, shape, surface texture, and the environmental conditions to which the concrete will be exposed.