For what reason is the maximum size of aggregate limited in concrete mixes?

The maximum size of aggregate is limited in concrete mixes primarily to minimize segregation and ensure proper packing of the materials. When larger aggregates are used, there is a higher likelihood that the aggregates may not uniformly distribute throughout the mix, leading to separation of the larger particles from the finer materials. This segregation can negatively affect the workability of the concrete and its strength after curing.

Moreover, ensuring proper packing is critical as it influences the concrete's density and the overall performance of the concrete. Smaller maximum sizes help to create a more uniform and cohesive mix, allowing for better bonding between the aggregates and the cement paste, which ultimately results in a stronger and more durable final product.

Other options may seem relevant but do not address the primary engineering concerns related to concrete performance. While aesthetic appeal, weight maximization, and cost considerations are important factors in concrete design and material selection, they do not directly relate to the functional necessity of aggregate size in maintaining the integrity and workability of the concrete mixture.