What is the role of aggregates in concrete?

Aggregates play a crucial role in concrete by providing volume, stability, and strength to the mix. They constitute the largest portion of the concrete composition, often making up about 60% to 80% of the total volume. The aggregates, which can be coarse (gravel, crushed stone) or fine (sand), help to control the shrinkage of the concrete during the curing process, as they limit the amount of paste needed to fill the voids.

By providing a solid framework within the concrete mixture, aggregates help distribute loads and resist cracking, ensuring that the concrete can handle the stresses it will face once set. The quality and type of aggregates used directly influence the concrete's overall performance, including its compressive strength, durability, and workability.

While aggregates may have other effects, such as impacting color or density, their primary function centers on enhancing the structural properties of concrete. Thus, focusing on their contribution to volume, stability, and strength directly addresses the essence of why aggregates are integral to concrete’s performance.