ACI Concrete Strength Testing Technician Practice Test

What should be eliminated to ensure proper capping of the concrete specimen?

1. Excess paste and voids

2. Moisture and dust

3. Drying and heat

4. Foreign materials and residue

The correct answer is: Excess paste and voids

To ensure proper capping of the concrete specimen, it is essential to eliminate excess paste and voids. This is critical because any excess paste can lead to an uneven surface and may cause inconsistencies in the strength testing results. Voids can create weak points in the capping layer, which can adversely affect the load distribution during compression testing. Achieving a smooth and even cap is crucial as it serves to transfer loads from the testing machine to the concrete specimen uniformly. Any imperfections, such as voids or excess material, can affect the integrity of the cap and thereby compromise the accuracy of the strength assessment. While moisture and dust, drying and heat, or foreign materials and residue might impact the testing conditions in various ways, the specific focus on the surface quality of the cap is paramount in ensuring a reliable test outcome. Therefore, removing any excess paste and voids directly correlates to obtaining a valid and meaningful measurement of the concrete's compressive strength.