What does "aggregate base course" refer to in highway construction?

The term "aggregate base course" specifically refers to a layer of granular material that is placed beneath the pavement to provide structural support. This layer is crucial in highway construction as it helps distribute loads from the pavement to the underlying subgrade soil, thereby enhancing the overall stability and longevity of the roadway. The materials used in an aggregate base course typically include crushed stone, gravel, and sand, which are compacted to form a solid foundation.

This granular layer also facilitates drainage, ensuring that water does not accumulate under the pavement, which can lead to weakening of the road structure over time. By providing both support and drainage, the aggregate base course is an essential component in the construction of highways, ensuring that the pavement above can effectively withstand traffic loads and environmental conditions.