Alabama Contractors License Practice Exam

What is the minimum compressive strength in psi for a concrete basement slab with negligible weathering potential?

1. 1,500

2. 2,000

3. 2,500

4. 4,000

The correct answer is: 2,500

The minimum compressive strength for a concrete basement slab with negligible weathering potential is 2,500 psi. This strength is typically appropriate for interior residential applications where the concrete is not exposed to severe environmental conditions, such as extreme freeze-thaw cycles or chemical exposure that could undermine its structural integrity. Concrete with a compressive strength of 2,500 psi is suitable for many foundation applications, as it provides a balance between workability and durability for typical basement conditions. While higher strength concrete, such as 4,000 psi, may offer more durability, particularly in harsher environments, the specifications for basement slabs with negligible weathering potential specifically indicate that 2,500 psi is sufficient to handle normal loads and conditions found in such spaces without the risk of premature failure. The lower strengths, such as 1,500 or 2,000 psi, tend to be inadequate for structural elements due to their limited load-bearing capabilities, which could compromise the overall integrity of the basement slab. Therefore, while 2,500 psi meets the necessary criteria for this application, options reflecting lower strengths do not provide the necessary resilience for a foundation.