Subbase is a layer of material that is placed on top of the native soil or subgrade during the construction of roads, highways, and other paved surfaces. It serves as a foundation or support layer for the overlying pavement layers. The main purpose of a subbase is to distribute the load from the pavement and provide stability and strength to the overall structure.
Some key functions and benefits of a subbase include:
1. Load distribution: The subbase helps to distribute the weight and traffic loads from vehicles evenly across the underlying soil or subgrade. This helps prevent excessive settlement and deformation of the pavement. 2. Moisture control: A well-constructed subbase can provide drainage and prevent water from accumulating within the pavement layers, which can lead to damage and deterioration. 3. Strength and stability: By providing a stable and compacted layer, the subbase improves the overall strength and load-bearing capacity of the pavement system. It helps to minimize the risk of rutting, cracking, and other types of pavement distress. 4. Uniform support: The subbase helps to create a uniform and consistent support layer for the pavement, ensuring that the overlying layers are adequately supported and protected.
The type of material used for the subbase can vary depending on the specific project requirements and local conditions. Common materials used for subbase include crushed stone, gravel, recycled concrete, and stabilized soil. The thickness and composition of the subbase are determined by factors such as traffic volume, soil conditions, and climate.