ACI Concrete Strength Testing Technician Practice Test

Against what types of plates should sulfur mortar cap plates be formed?

1. Stone or plastic plates

2. Wood or acrylic plates

3. Metal or stone plates

4. Glass or ceramic plates

The correct answer is: Metal or stone plates

Sulfur mortar cap plates are specifically designed to be formed against non-porous materials that will prevent the mortar from adhering to them during the curing process. Metal or stone plates are ideal for this purpose because they possess the necessary smoothness and non-absorptive characteristics that allow for easy removal of the cap after curing. Metal plates provide a robust and smooth surface that facilitates even capping, ensuring that the ends of concrete test specimens are perfectly flat and accurately prepared for strength testing. Similarly, stone plates, which are typically non-porous, also serve the same purpose, offering a stable surface and minimizing the risk of contamination that could affect test results. Other materials like wood or acrylic can absorb moisture or may not provide the required smoothness, leading to imperfections in the cap that could adversely impact the test measurements. Glass or ceramic plates, while smooth, are not commonly used due to their brittleness and potential breakage, which can lead to safety hazards. Thus, the choice of metal or stone plates ensures both durability and accuracy in preparing sulfur mortar cap plates.