ACI Certification Practice Exam

After how many strokes should the top layer be checked for sufficient concrete?

1. 15 strokes

2. 20 strokes

3. 25 strokes

4. 30 strokes

The correct answer is: 25 strokes

The correct answer is that the top layer should be checked for sufficient concrete after 25 strokes. This guideline is based on standard practice and is designed to ensure that the concrete is adequately consolidated. After this number of strokes, visual inspection can reveal whether the concrete has filled the space properly and achieved the desired consistency. Insufficient strokes could lead to areas with inadequate compaction, which may compromise the structural integrity of the concrete. The choice of 25 strokes reflects a balance between ensuring thorough consolidation while avoiding fatigue or overworking the concrete, which could introduce air pockets or other inconsistencies. This practice is critical in various concrete placement situations to enhance the overall quality and performance of the concrete structure.