ACI Concrete Field Testing Technician - Grade I Practice Exam

Up to how many hours after molding should test specimens be stored at a temperature range of 60 to 70 degrees F?

1. 24 hours

2. 48 hours

3. 12 hours

4. 8 hours

The correct answer is: 48 hours

The correct answer is that test specimens should be stored at a temperature range of 60 to 70 degrees Fahrenheit for up to 48 hours after molding. This practice is crucial because it allows the concrete to gain initial strength and stabilize before being transferred to a more controlled curing environment. During the first 48 hours, the hydration process begins, and maintaining a consistent temperature within this range helps ensure that the chemical reactions occurring within the cement paste are optimal. If the specimens are exposed to temperatures outside this range, it can adversely impact the curing process, leading to inconsistent results in strength testing and potentially affecting the overall quality of the concrete. Storing the specimens for this recommended duration aids in achieving reliable and reproducible results when conducting tests, such as compressive strength tests, which follow established standards in concrete testing protocols.