General Contractor Practice Exam

What is the required minimum compressive strength of concrete with 1% air entertainment in severe conditions?

1. 2000 PSI

2. 2500 PSI

3. 3000 PSI

4. 3500 PSI

The correct answer is: 2500 PSI

In severe exposure conditions, concrete must be designed to resist various factors that could compromise its integrity, such as freeze-thaw cycles, sulfates, and other aggressive environmental influences. The American Concrete Institute (ACI) provides guidelines on the minimum compressive strength for concrete based on the exposure conditions and the intended use of the concrete. For concrete with 1% air entrainment, which is a common practice to enhance freeze-thaw resistance, the minimum compressive strength required is typically set at 2500 PSI. This strength level ensures that the concrete can withstand the repeated stress from environmental conditions while providing durability over its intended service life. Higher strength grades, such as 3000 PSI or 3500 PSI, would be suitable for even more demanding conditions or specific applications, but for standard severe conditions, 2500 PSI is the minimum requirement as it meets the baseline durability and performance expected in such environments.