What size sieve must a 4-inch base course for a below grade concrete floor pass through?

For a 4-inch base course used in below grade concrete floors, the correct size sieve that the material must pass through is 2 inches. This requirement is based on construction standards and practices that ensure the material provides adequate support and compaction for the concrete slab above while also allowing for proper drainage and prevention of voids that can lead to future settling or cracking.

The size of the sieve indicates the largest particle size that can be included in the base course material. A 2-inch sieve allows for larger aggregate to provide strength and stability without compromising the ability of the material to be compacted adequately. This helps to create a solid base for the concrete, which is essential for the durability and longevity of a below grade concrete floor.

In contrast, larger sieve sizes like 3 inches or 4 inches would permit larger aggregates that may not adequately interlock and compact, which can lead to a weak foundation for the concrete slab. A 1-inch sieve may not allow for sufficient aggregate size to maintain stability in the base course. Therefore, adherence to the 2-inch sieve requirement is critical for achieving the proper composition and performance of the base course material.