1. It is to close a certain layer and play the role of water retention and waterproof;
2. It plays the role of transition and effective connection between the base layer and the asphalt surface layer;
3. It is the reinforcement and reinforcement of a certain layer of the surface of the road that is damaged and segregated;
4. Before the base layer is laid on the asphalt surface layer, traffic should be temporarily opened to prevent damage to the base layer due to weather or vehicles.