Aggregates are an essential component of concrete, consisting of inert granular materials such as sand, gravel, or crushed stone. They are a broad category of materials, with particles that are typically coarse-grained or medium-grained. Generally, aggregates are considered to be an inert filler in a concrete mix. However, a closer look reveals the significant role that aggregates play in influencing the properties of both fresh and hardened concrete.
Variations in gradation, maximum size, unit weight, and moisture content can all affect the character and performance of the concrete mix. This article provides a summary of the most important factors to consider when selecting and dosing concrete aggregate. Alternative sources of aggregates or additional aggregate mixtures can be explored to achieve the ideal gradation that provides the best workability, pumpability, shrinkage reduction, and economy (Figure).