Alabama Contractors License Practice Exam

How should concrete be consolidated when using stay-in-place forms for foundation?

1. With a shovel

2. Internal Vibration

3. None required

4. Tamping

The correct answer is: Internal Vibration

Using internal vibration to consolidate concrete when using stay-in-place forms for a foundation is essential because this method effectively eliminates air bubbles and voids that can lead to weak spots in the cured concrete. Internal vibrators work by creating localized vibrations that help the concrete flow into place, ensuring full compaction around reinforcing bars and the forms themselves. Stay-in-place forms can create a situation where the concrete has limited access to external vibration methods, so internal vibration becomes necessary to achieve the desired density and strength of the concrete. This technique is particularly important in managing the properties of concrete to maximize its structural integrity, especially in foundational applications where load-bearing capacity is critical. Other methods, such as using a shovel or tamping, would not provide the necessary compaction results. Shoveling may leave air pockets and insufficiently consolidate the mix, while tamping can lead to uneven compaction and is not suitable for all types of concrete pours, particularly in thicker or heavily reinforced applications. Therefore, internal vibration is the most effective and recommended method in this scenario.