1, water-stable layer is the transition layer between hard pavement and soil subgrade, which is effectively combined with pavement and subgrade to form an organism.

2. The water-stable layer has certain strength and rigidity. Higher than the subgrade and lower than the pavement, it can not only ensure a certain pavement thickness, meet the load bearing, but also reduce the construction cost.

3. The water-stable layer can evenly disperse the vehicle load borne by the pavement to the subgrade, and has certain toughness.

4. Gravel coarse sand in water-stable layer has good drainage capacity, which can reduce subgrade water accumulation and its bearing capacity.