ACI Concrete Field Testing Technician - Grade I Practice Exam

What must be done if the concrete drops below the top of the slump mold during rodding?

1. Leave it as is

2. Add additional concrete above the top of the mold

3. Remove the concrete

4. Pause and wait for it to settle

The correct answer is: Add additional concrete above the top of the mold

When concrete drops below the top of the slump mold during the rodding process, it is essential to add additional concrete above the top of the mold. This action ensures that the full volume of the concrete sample is properly represented within the mold. The slump test requires that the mold be completely filled to provide an accurate measurement of the concrete's consistency and workability. If the concrete level drops, it can lead to an inaccurate slump measurement, as the test relies on how the concrete behaves when the mold is removed. By adding the appropriate amount of concrete to bring the level back up, testers can ensure they capture the true properties of the concrete being tested. It's crucial in quality control and assurance processes in concrete testing to maintain accuracy and reliability, which is facilitated by following this step.