Natural shotcrete finish when an aggregate rich shotcrete mix is sprayed with an industrial machine.
This rough surface would be expected on the interior of a big dome built with an industrial shotcrete machine. There’s nothing wrong with this surface, but fewer troughs and ridges in the dimpled finish should be seen on the interior of smaller domes when an expert workman sprays the finish coats of shotcrete using a smaller nozzle and a shotcrete mix without aggregate.