ACI Concrete Field Testing Technician - Grade I Practice Exam

When raising the slump mold, what should NOT be done?

1. Rotate or twist the mold

2. Lift the mold straight up

3. Wait longer than necessary

4. Use two hands for lifting

The correct answer is: Rotate or twist the mold

When raising the slump mold, it is crucial to lift it straight up without any twisting or rotating motions. Twisting the mold while lifting can disturb the concrete sample inside, leading to inaccurate slump measurements. The slump test relies on the concrete retaining its shape and integrity during the process, so any motion that alters the position of the concrete can result in a misinterpretation of its workability. Lifting the mold straight up ensures that the concrete maintains its form and that the slump can be measured accurately. Waiting longer than necessary is typically not advisable as it can lead to segregation or changes in the concrete's properties, while using two hands is often encouraged for control and stability during the lifting process. Overall, maintaining the integrity of the concrete sample during this critical phase of the test is essential for obtaining reliable results.