What impact does gradation have on aggregate base performance?

Gradation has a critical role in determining the performance of aggregate base materials. The distribution of different particle sizes in an aggregate mix, or gradation, directly impacts various properties essential for the functionality of the base layer.

A well-graded aggregate will typically have a range of particle sizes, allowing smaller particles to fill the voids between larger particles. This packing density enhances the overall stability of the material. Additionally, proper gradation influences drainage characteristics by promoting effective water movement through the material, reducing the risk of water accumulation and associated issues like weakening of the base or erosion.

Conversely, poorly graded aggregates may have too much of a certain size, leading to larger void spaces that can trap water or compromise stability under load. Therefore, understanding and controlling the gradation of aggregates used in base construction is essential for ensuring that the pavement layers perform as intended over their lifespan.