Shotcrete is a placement method for concrete. All normal concrete experiences drying shrinkage that creates a volume change in the hardened concrete. Pools will also experience volume change in the concrete due to thermal changes, especially summer to winter seasonal swings. Contraction and expansion joints are common in all kinds of concrete liquid-containing structures especially with walls of this length. Though we can’t provide a firm design recommendation you should consider these factors:
- What are the weather conditions when the pool is anticipated to be built? If during hot summer months, could there be enough seasonal temperature swing to require expansion joints?
- If expansion joints wouldn’t be needed would contraction joints be needed to handle anticipated temperature swings, and drying shrinkage?
- Will the pool be empty for extended times (this could lead to more shrinkage or direct exposure to solar gain or cold conditions?
- Is the pool to be kept full or empty during the winter months? (if the pool is in a geographic region where extending freezing conditions are prevalent)
Overall, the design for a shotcrete pool should be the same as one for a cast concrete pool.