ACI Concrete Strength Testing Technician Practice Test

Are plaster of Paris and mixtures of plaster of Paris with portland cement suitable high-strength plasters?

1. Yes, they are suitable

2. No, they are not suitable

3. Only if mixed correctly

4. Only in small quantities

The correct answer is: No, they are not suitable

Plaster of Paris, while useful in various applications such as mold making and finishing, does not possess the mechanical properties required for high-strength applications when used alone. When it is mixed with Portland cement, the resulting mixture may not reach the high strength levels that are typically demanded in construction standards. High-strength plasters need to have specific characteristics such as durability, resistance to cracking, and adequate compressive strength, which plaster of Paris alone or in combination with Portland cement fails to provide sufficiently. Additionally, high-strength plasters are often formulated with specific additives and design considerations to enhance their performance, making them significantly more robust than simple plaster of Paris mixtures. Therefore, relying on these materials for high-strength applications is not advisable, as they do not meet the necessary criteria for strength, durability, and structural integrity needed in construction and engineering practices.