Massachusetts Unrestricted Construction Supervisor License Practice Test

When used as an ingredient in shotcrete, can coarse aggregate have a diameter of 7/8 inch?

1. Yes

2. No

3. Only in specific conditions

4. Only if mixed with sand

The correct answer is: No

In shotcrete applications, the size of the aggregate used is critical for achieving the desired strength and consistency of the mixture. The standard practice for shotcrete typically requires using fine aggregates or coarse aggregates with a maximum size of up to 3/8 inch. Using a coarse aggregate with a diameter of 7/8 inch exceeds this size limit, which can adversely affect the pumping and application of the shotcrete, leading to issues such as segregation and insufficient bonding to the substrate. Maintaining smaller aggregate sizes allows for better compaction and a smoother application surface. This is essential because shotcrete is often applied in layers, and larger aggregates can disrupt the layer's cohesiveness and overall integrity. Therefore, the use of aggregate larger than the recommended size does not align with best practices for shotcrete applications, confirming that the correct answer is that coarse aggregate with a diameter of 7/8 inch should not be used in shotcrete mixtures.