There is no special requirement for shotcrete placement in pools. Basically, you are building a watertight structural concrete shell. Concrete should be a minimum 28-day compressive strength of 4000 psi (28 MPa). Most shotcrete uses a 3/8 in. (10 mm) maximum coarse aggregate size due to our small diameter delivery lines. The coarse aggregate (rock) being about half the weight of the sand content. We typically need a cement-rich paste so minimum cementitious content (cement, fly ash, slag) of 700 lb/yd3. We also need a low w/cm ratio for the ability to stack in the wall so maximum of 0.45, with most wet-mix concrete 0.42 or less. You may find our ASA Position Statements for our Pool and Recreational Committee helpful in providing more detail. Our current statements include:
Compressive Strength Values of Pool Shotcrete
Shotcrete Terminology
Sustainability of Shotcrete in the Pool Industry
Watertight Shotcrete for Swimming Pools
Monolithic Shotcrete for Swimming Pools (No Cold Joints)
Forming and Substrates in Pool Shotcrete
Curing of Shotcrete for Swimming Pools
You can find the position statements freely available at www.shotcrete.org/products-services-information/resources/.