Base aggregate is the crushed, well graded, aggregate layer, typically ¾” -0, placed in the construction process just prior to placing the base lift of asphalt (in thick asphalt design sections) or the final working asphalt surface in sections of 3” of asphalt or less. The base lift serves many purposes; It acts as a leveling layer graded to tight tolerances so that the asphalt surface can be placed in a consistent depth. It provides a stable surface, with relatively low moisture content to prevent frost heaving. Finally, it provides a solid base layer so that adequate compactive force can be applied to the asphalt to achieve proper compaction to ensure a long-lasting asphalt pavement.