What factor should be considered when selecting aggregates for concrete?

When selecting aggregates for concrete, one of the primary factors to consider is the particle size and shape. The particle size greatly influences the workability, strength, and durability of the concrete mix. The proper distribution of different sizes ensures that the aggregate skeleton is tightly packed, which reduces the voids and optimizes the concrete's mechanical properties.

Additionally, the shape of the aggregates can affect how they pack together and bond with cement paste. Angular shapes tend to lock together better than rounded shapes, which can lead to a stronger concrete. Understanding the characteristics of the aggregates being used is crucial to achieving the desired performance in the concrete, highlighting the importance of assessing particle size and shape.

While other factors like cost, geographical location, and color may have relevance in specific scenarios, they do not directly impact the physical and chemical properties of concrete in the same way that particle size and shape do.