What is the required minimum compaction for sub-base and base of crushed stone bases and sub-bases for flexible pavement?

The required minimum compaction for sub-base and base layers of crushed stone bases and sub-bases for flexible pavement is established at a threshold of not less than 95% of the maximum laboratory dry density. This standard ensures that the materials have adequate density, stability, and load-bearing capacity when integrated into flexible pavement systems.

Achieving a compaction level of 95% is vital for several reasons. Firstly, it helps to mitigate issues related to settlement under load, which is crucial for maintaining the structural integrity of the pavement over time. Secondly, proper compaction minimizes the air voids within the material, reducing potential water infiltration that could lead to erosion or weakening of the pavement. Additionally, sufficient compaction enhances the overall performance of the pavement structure, ensuring longevity and reliability.

While higher compaction levels exist, such as 100% or even 105%, these are generally not required as they can lead to unnecessary stresses in the material and potentially create complications during the construction process. Therefore, the focus is on achieving that critical threshold of 95% to balance performance and practicality in flexible pavement design.