Alabama Contractors License Practice Exam

Backfill in the annular space surrounding retaining wall columns must be concrete with a compressive strength of at least how many psi?

1. 2,000 psi

2. 3,000 psi

3. 4,000 psi

4. 5,000 psi

The correct answer is: 2,000 psi

The correct standard for backfill in the annular space surrounding retaining wall columns necessitates that the concrete used has a minimum compressive strength of 2,000 psi. This strength ensures adequate support for the columns while maintaining stability and structural integrity. Concrete with this compressive strength is generally sufficient for various foundation applications, including those where the construction supports significant loads such as retaining walls. While higher strength options exist, they might impose unnecessary costs without providing additional benefits for this specific use case. Hence, the established requirement of 2,000 psi is poised to offer an effective balance of performance and economical use of materials. In contrast, the other options, which specify higher compressive strengths, could be considered excessive for this particular application. Using concrete with a strength exceeding 2,000 psi might complicate project specifications and increase costs without yielding a notable advantage for the structural performance of the retaining wall columns.