Earthwork
Base Course
The layer of compacted granular material directly below a paved surface, providing strength and load distribution to the pavement above.
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In the Field
Base course is typically dense-graded aggregate (DGA) or crushed limestone, compacted to 98–100% Proctor. It must be shaped to the finished grade before paving. Any irregularity in the base shows up in the finished pavement.
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Rule of Thumb
Base course thickness for parking lots is typically 6 inches; for roads carrying heavy trucks, 8–12 inches or more depending on the pavement design.