Which aggregate characteristic contributes to minimal water absorption in concrete mixes?

Well-graded aggregates play a significant role in minimizing water absorption in concrete mixes. When aggregates are well-graded, it means that they consist of a wide range of particle sizes that fit together more efficiently, reducing the void spaces between them. This efficient packing helps to create a denser concrete matrix, which in turn decreases the amount of water that can be absorbed.

A well-graded aggregate mix allows for optimal interlock between aggregate particles, leading to lower permeability. This is crucial because high permeability can lead to increased water absorption, negatively affecting the durability and strength of the concrete. By minimizing voids within the aggregate assembly, the concrete mix can maintain a lower overall water-cement ratio, which enhances its performance and longevity.

Other factors like coarse aggregate grade, fine aggregate size, and aggregate cleanliness can influence concrete performance, but they do not directly influence water absorption in the same way that a well-graded aggregate does. Coarse aggregate grading may affect the strength but doesn't guarantee minimal water absorption. Fine aggregate size might influence workability but not specifically address voids as effectively as well-graded aggregates. Lastly, aggregate cleanliness is important for adhesion and bonding in the mix, but its impact on water absorption is secondary to the benefits provided by a well-