Are there industry-standard design guides for the design of formwork for shotcrete? I have reviewed the technical questions and found the article “Dynamic Forces during Shotcreting Operations” by Frederic Gagnon and Marc Jolin, but the impact loads in this article are quite small (approximately 90 lb [40 kg] per nozzle application), and I feel uncomfortable using that as the sole design load. However, since there is little to no hydrostatic load from shotcrete, I am having a difficult time coming up with a reasonable design load in lieu of this.

Shotcrete placement produces very localized pressure on the one-sided forms we typically use. The 90 lb (40 kg) is a reasonable figure when shooting directly against the form. If shooting thick walls, we typically use a benching approach for placement that puts most of the force directly on the supporting floor (or earth) and putting little force on the form. Thus, the form is more of a way to define the back surface. You will often see shotcrete forms in lower-height applications using thin forming materials such as Masonite, pegboard, or even a stay-form for the formed surface. Often, the larger load controlling the design on a form may be the wind loads expected during the construction period.