Florida DOT Concrete Batchman/Operator Practice Exam

Which of the following is a benefit of air entrainment in concrete?

1. Increased weight

2. Improved workability

3. Higher water absorption

4. Reduced mixing time

The correct answer is: Improved workability

Air entrainment in concrete significantly enhances workability, which refers to how easily the concrete can be mixed, placed, and finished. When microscopic air bubbles are introduced into the concrete mix, they improve the flow and cohesion of the mixture. This results in a smoother and more uniform consistency, making it easier for operators and laborers to work with the concrete. The presence of these air pockets allows for better handling during placement and finishing processes, which is particularly beneficial in larger pours or complex forms. As the air bubbles provide additional space within the mix, they help to reduce internal friction among the aggregates, thereby enabling easier compaction and movement. In contrast, the other choices do not represent the benefits of air entrainment. Increased weight would be counterintuitive, as air entrainment typically results in a lighter concrete. Higher water absorption could imply a detrimental effect on the concrete's durability, which is not a desired outcome of air entrainment. Additionally, reduced mixing time is not generally associated with the use of air-entraining agents; in fact, achieving proper mixing may take slightly longer to ensure the bubbles are evenly distributed throughout the mix.