ACI Certification Practice Exam

After the final writing, should the sides of the slump mold be tapped lightly with the tamping rod?

1. True

2. False

3. Only if necessary

4. Only with permission

The correct answer is: False

The process of measuring slump in concrete involves the use of a slump cone, which is a specific type of mold that tapers from a larger diameter at the top to a smaller diameter at the bottom. After the concrete is filled into the mold, it is typically leveled off at the top without any additional manipulation, such as tapping the sides. Tapping the sides of the slump mold with the tamping rod could introduce air into the mix, potentially altering the consistency of the concrete and skewing the slump measurement. The purpose of measuring the slump is to obtain a direct assessment of the concrete's workability in its natural, unaltered state after it has been compacted appropriately within the cone mold. Therefore, not tapping the sides is crucial for ensuring accurate and reproducible slump measurements that reflect the true workability of the concrete mix used.