Why is gradation significant in the selection of aggregates for concrete?

Gradation is a critical factor in the selection of aggregates for concrete because it plays a significant role in ensuring optimal packing of the materials. When aggregates are properly graded, they can fit together more effectively, which minimizes the voids or spaces between the particles. This enhanced packing density not only reduces the amount of cement required to fill those voids but also contributes to the overall strength and durability of the concrete.

When the aggregate gradation is ideal, it allows for better use of the cement paste, leading to a more efficient mix that has the potential for improved workability and reduced shrinkage during curing. Additionally, concrete with well-graded aggregates tends to perform better under various loads, providing greater structural integrity. Therefore, understanding and applying correct gradation is essential for achieving high-quality concrete that meets design specifications and performance expectations.