What is the maximum aggregate size for shotcrete?

What is the maximum aggregate size for shotcrete?

• A. 12.7 mm (1/2 in)
• B. 19 mm (3/4 in)
• C. 9.5 mm (3/8in)
• D. 6.35 mm (1/4in)

Answer: (B)

The maximum aggregate size for shotcrete is 3/4 inch (19 mm). This limit exists because shotcrete must be pumped through hoses and delivered through a nozzle, so the aggregate must be small enough to flow smoothly. If the aggregate were larger, it could clog pumps, cause inconsistent distribution, increase rebound, and produce a rough surface with weaker bonding. Using up to 3/4 inch keeps the mix workable for nozzle placement while still providing required strength. Smaller sizes are used for more delicate placements, but 3/4 inch is the standard maximum.

The maximum aggregate size for shotcrete is 3/4 inch (19 mm). This limit exists because shotcrete must be pumped through hoses and delivered through a nozzle, so the aggregate must be small enough to flow smoothly. If the aggregate were larger, it could clog pumps, cause inconsistent distribution, increase rebound, and produce a rough surface with weaker bonding. Using up to 3/4 inch keeps the mix workable for nozzle placement while still providing required strength. Smaller sizes are used for more delicate placements, but 3/4 inch is the standard maximum.