Shotcreting offers the builder and designer more flexibility and design creativity than any other pool construction method. However, it also requires excavating the site, then shaping, reinforcing, and shooting the concrete shell--laborious and demanding work. To ensure that all that hard work isn't wasted, pool builders should pay close attention to two steps that are sometimes overlooked--curing and, during hot or cold weather, protecting the shotcrete.
Section 3.8 of the American Concrete Institute's "Specification for Shotcrete" (ACI 506.2-95) gives curing requirements that are good guidelines for shotcreted pool shells. The specification lists several curing methods: ponding or continuous sprinkling; covering with an absorptive mat or sand kept continuously wet; covering with impervious sheet material; applying curing compounds.
The ACI shotcrete specification prohibits placing shotcrete when the temperature of wet-process shotcrete is above 90 degrees Fahrenheit and that of dry-process shotcrete is above 100 degrees Fahrenheit. Unless measures are taken to protect the shotcrete, shooting must be discontinued when the ambient temperature is 40 degrees Fahrenheit and falling.