ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the next step after rodding each layer of a concrete sample?

1. Pour additional water

2. Tap the sides of the measure with a mallet

3. Wait for the sample to settle

4. Add more concrete immediately

The correct answer is: Tap the sides of the measure with a mallet

After rodding each layer of a concrete sample, the next step is to tap the sides of the measure with a mallet. This action is performed to consolidate the concrete within the measure by eliminating any air bubbles that may have been entrapped during the rodding process. Proper consolidation is critical to ensuring that the sample accurately represents the properties of the concrete mix, as it helps achieve a uniform density and reduces the likelihood of voids which could interfere with testing results. Rodding is meant to break apart the larger agglomerates of aggregate within the mix, while tapping with a mallet enhances the process by allowing the concrete to settle and fill any gaps resulting from the rodding. This ensures that the sample taken for testing is as representative as possible of the actual concrete mixture. Actions like pouring additional water, waiting for the sample to settle, or adding more concrete immediately would not be appropriate after rodding, as they could alter the mix's composition or consistency, ultimately compromising the integrity of the sample being tested.