ACI Concrete Strength Testing Technician Practice Test

What type of load application is required by the testing machine in ASTM C39?

1. Intermittent load application

2. Continuous load application

3. Variable load application

4. None of the above

The correct answer is: Continuous load application

In the context of ASTM C39, which deals with the standard test method for compressive strength of cylindrical concrete specimens, the requirement for a continuous load application is fundamental to accurately determining the compressive strength of concrete. Continuous load application ensures that the load is applied steadily and uniformly until the specimen fails. This process allows for a clear understanding of how the concrete behaves under increased stress, avoiding any abrupt changes that might impact the data collected. A continuous approach minimizes the risk of shock loading, which could cause premature failure or misleading results. Intermittent load application could lead to inconsistent stress distribution within the concrete specimen, while variable loads could complicate the interpretation of the strength results. Therefore, the continuous loading method is critical for maintaining the integrity of the test results and ensuring consistent performance across different concrete samples. This precise loading method aligns with the intent of ASTM standards to achieve reliable and valid test outcomes.