What is the Percent Maximum Density for modified base subgrade material?

The Percent Maximum Density for modified base subgrade material is typically understood to be 98 percent. This standard is used in construction and earthwork to ensure that the material has been compacted adequately to achieve optimal strength and minimal settlement over time.

This level of compaction is essential for providing a stable foundation for various structures such as roads, sidewalks, and paving, as it helps to reduce the risk of future issues like displacement, cracking, or instability due to insufficient support. Achieving 98 percent of maximum density is a common requirement in many construction specifications to ensure the longevity and durability of the subgrade material under load.

This standard is based on tests such as the Modified Proctor Test, which measures the moisture-density relationship of soil and other materials to establish the maximum density that can be achieved. This process involves compacting the material into a mold at different moisture contents to find the optimal moisture level that allows the material to achieve its highest density when worked and compacted.