ACI Concrete Field Testing Technician - Grade I Practice Exam

How many times should the vibrator be inserted into each layer during consolidation?

1. One

2. Two

3. Three

4. Four

The correct answer is: Three

The correct number of times to insert the vibrator into each layer during consolidation is three. This practice is essential in ensuring that the concrete is properly compacted, which helps to eliminate air voids and achieve a uniform mix. The goal of using a vibrator is to allow the concrete to flow and settle into the forms, which is critical for maximizing strength and durability in the final hardened product. Inserting the vibrator three times into each layer typically ensures that the concrete is adequately consolidated without over-vibrating, which can lead to segregation of the mix components. Each insertion should be done quickly and with a slight withdrawal motion, allowing the vibratory motion to work through the mix and enhance its flowability. This technique supports achieving a well-compacted layer that adheres properly to subsequent layers, contributing to the overall integrity of the structure.