In many concrete construction projects, it is common to place a layer of well-compacted gravel or crushed stone beneath the concrete. This layer serves as a base or subbase and provides several benefits:
Load Distribution: A layer of gravel helps distribute the load of the concrete evenly over the subgrade (the natural soil or foundation) beneath it. This helps prevent settlement and cracking of the concrete.
Drainage: Gravel acts as a drainage layer, allowing excess water to move away from the concrete and prevent water from being trapped beneath the slab. Proper drainage is important for preventing erosion and moisture-related issues that can damage the concrete.
Stability: Gravel provides a stable and well-draining foundation, which is particularly important in areas with expansive soils or in regions prone to freeze-thaw cycles. It helps prevent soil movement and the potential for heaving or settling of the concrete.
Protection Against Frost: In colder climates, a layer of gravel can help mitigate frost heave by allowing water to drain away from the concrete. This helps prevent the expansion of freezing water from damaging the concrete.
Slope Correction: Gravel can be used to correct slopes or uneven subgrades, ensuring that the final concrete surface is level and properly graded.
Preventing Soil Erosion: Gravel can help control soil erosion, which is especially important in areas with heavy rainfall or surface water runoff.
While gravel is commonly used as a base or subbase for concrete, the specific requirements for the type and thickness of the gravel layer can vary depending on the project, local conditions, and engineering recommendations. It’s essential to follow the guidance provided by a qualified concrete contractor or engineer to ensure that the gravel layer is appropriate for your specific project.