ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the correct temperature range for storing concrete test specimens?

1. -5°C to 5°C

2. 10°C to 20°C

3. 20°C to 30°C

4. 5°C to 35°C

The correct answer is: 5°C to 35°C

The proper temperature range for storing concrete test specimens is 5°C to 35°C. This range is crucial because it ensures that the specimens cure under conditions that closely mimic the intended environmental conditions of the concrete once placed in service. Storing specimens within this range helps to achieve accurate and reliable strength and durability results, as extreme variations in temperature can adversely affect the hydration process of the cement and the overall development of strength in the concrete. In colder temperatures (below 5°C), the hydration process slows significantly, which can lead to incomplete curing and ultimately weakened concrete. Conversely, at temperatures above 35°C, there is a risk of rapid evaporation of water from the surface of the concrete, which can result in superficial drying and the possibility of cracking or other forms of distress. Maintaining the specimens within the specified temperature range helps to create a controlled environment that supports uniform curing conditions, which is essential for ensuring that the test results accurately reflect the performance characteristics of the concrete mix under typical field conditions. This practice aligns with industry standards and recommendations by organizations such as ASTM and ACI, emphasizing the importance of temperature control in the curing of concrete specimens.