Florida DOT Concrete Batchman/Operator Practice Exam

For agitating trucks with water reducers or retarders, what is the maximum time allowed from initial introduction of water to complete depositing of concrete?

1. 60 minutes

2. 75 minutes

3. 90 minutes

4. 120 minutes

The correct answer is: 90 minutes

The correct answer is based on the recommended guidelines and best practices for maintaining the quality of the concrete mix during transit. When using water reducers or retarders, it is crucial to ensure that the concrete remains workable and does not lose its intended performance characteristics within a specific timeframe. For agitating trucks, the maximum time allowed from the initial introduction of water to the complete depositing of concrete is 90 minutes. This timeframe is established to prevent the effects of setting and to maintain the integrity and workability of the concrete. Longer periods can lead to issues such as reduced strength, and workability, or can cause the mix to exceed its setting time, compromising the final quality of the poured concrete. Understanding this limit helps operators ensure that the concrete delivered is consistent with the specifications needed for the project at hand, supporting overall construction quality and reliability. Adhering to this timeline also helps in managing the mixing operations effectively, ensuring that the concrete adheres to the necessary standards before reaching the job site.