After the arch frame is erected the wet shotcrete is required Here’s why and how it is typically done: Why wet shotcrete is applied after arch frame erection Stabilizes surrounding rock The arch frame provides a skeleton, but without shotcrete the surrounding rock can still loosen or fall. Wet shotcrete quickly seals and reinforces the rock mass. Forms a composite support system Shotcrete steel arch rock bolts work together as a whole. Shotcrete fills the gap between the arch and the rock surfac