What type of strength is specifically not to exceed 300 psi in excavatable CLSM?

The correct answer is compressive strength. In the context of Controlled Low-strength Material (CLSM), which is often used as a backfill material for excavated areas, there are specific guidelines for strength properties to ensure proper performance.

The limit of 300 psi (pounds per square inch) for excavatable CLSM refers to its compressive strength, which is the ability of the material to withstand axial loads without failing. This level of strength is sufficient to support light traffic and loads while still allowing for easy excavation when necessary.

Maintaining the compressive strength limit is crucial for ensuring that the material remains workable and can be excavated if future construction or repairs are needed. Exceeding this strength could result in difficulties during excavation, which is one of the primary benefits of using CLSM—its ease of removal compared to traditional compacted fills while still providing a stable, structural base.