Explain C1 material in design flexible layer. In English language

In the design of flexible pavement layers, C1 material typically refers to a cement-bound granular material or a cement-stabilized material. This means it's a mixture of granular aggregates (like crushed stone or gravel) that has been mixed with a small percentage of cement and water, then compacted.

Here's its role and characteristics:

• Location: C1 material is commonly used as a sub-base or base layer in flexible pavements, positioned directly above the subgrade and below the asphalt concrete layers.
• Properties: The addition of cement significantly increases the strength and stiffness of the granular material compared to an unbound granular layer. It also improves its durability and resistance to deformation under traffic loading.
• Purpose in Design:
  • Load Distribution: It provides a strong, rigid platform that effectively distributes traffic loads over a wider area to the underlying subgrade, reducing stresses on the weaker soil.
  • Reduced Thickness: Due to its high stiffness, using a C1 layer can allow for a reduction in the required thickness of the more expensive asphalt concrete layers above it, leading to cost savings.
  • Improved Performance: It helps prevent rutting and other forms of distress in the pavement by providing a stable foundation.
  • Moisture Resistance: Cement stabilization can also improve the material's resistance to moisture, which is crucial for long-term pavement performance.

In essence, C1 material acts as a high-performance structural layer that bridges the gap between the subgrade and the asphalt surface, enhancing the overall strength and longevity of the flexible pavement.