ACI Certification Practice Exam

What three tests must always be performed when making test specimens?

1. Temperature, hardness, viscosity

2. Temperature, slump, air content

3. Temperature, strength, elasticity

4. Temperature, density, shrinkage

The correct answer is: Temperature, slump, air content

When creating test specimens for concrete, the three essential tests that must always be performed are related to the fresh concrete's workability and quality. These tests are temperature, slump, and air content. Temperature measurement is vital because it significantly influences the concrete's setting time and ultimate properties. A consistent temperature ensures that the concrete's behavior during curing remains predictable. The slump test is essential for assessing the workability of fresh concrete. It measures how much a concrete mixture slumps under its own weight, providing insight into its consistency and flowability. This is crucial for determining if the concrete will adequately fill forms and achieve the desired strength. Air content testing evaluates the amount of entrained air in the concrete mix. This is important because entrained air contributes to the durability and freeze-thaw resistance of concrete, particularly in cold climates. Monitoring air content ensures that the concrete performs well in various environmental conditions. Together, these tests provide a comprehensive view of the concrete mix's properties before it sets, ensuring that it meets required specifications and standards for performance.