North Carolina Building Contractor License Practice Exam

How long do you have, from batching at the plant to complete discharge on the jobsite, for ready mixed concrete?

1. 1 hour

2. 2 hours

3. 2.5 hours

4. 3 hours

The correct answer is: 2.5 hours

The correct response indicates that the allowable time from batching at the plant to complete discharge on the jobsite for ready mixed concrete is 2.5 hours. This timeframe is critical for ensuring that the concrete maintains its workability and performance characteristics. Beyond the specified duration, chemical reactions in the concrete mix can begin to change its properties, which might lead to difficulties in achieving the desired strength and durability. Factors like ambient temperature and the specific mix design can influence the setting time, but the general standard for ready mixed concrete is that it should be discharged within 2.5 hours of batching to ensure that the quality is not compromised. Managing this timeline is essential for contractors to meet project specifications and maintain compliance with industry standards, ensuring that the final product achieves the necessary strength and longevity as intended.