08/07/2026
Flexible pavement.
Subgrade:
This is the natural, compacted soil at the very bottom. It is the ultimate foundation that supports the entire road. If this soil is weak, the whole road fails.
Subbase Layer:
Usually made of crushed stone, gravel, or slag. This acts as a primary load-bearing layer and provides a drainage path so water doesn't pool under the road.
Base Layer:
Placed directly underneath the pavement surface, this layer uses high-quality crushed aggregate or asphalt-treated mixes. It does heavy lifting by spreading the traffic weight evenly over the subbase.
Binder Course:
An intermediate layer of asphalt aggregate mix that bridges the gap between the rough base layer and the smooth top layer.
Surface Course: The top layer you actually drive on. Made of dense asphalt concrete, it is designed to resist skidding, withstand high friction, and seal out water so rain can't seep into the lower layers.
