Abstract: A method for cutting an arcuate groove in an uncured concrete coating on an arcuate surface. A jet stream of water is directed at the coating along a line extending tangentially of the surface in a downward direction. The object is rotated at a relatively low speed in relation to the stationary water jet. The invention also encompasses a method of applying a concrete coating to pipe wherein after the cement is forced onto the pipe a wrapping material is wound around the pipe in a spiral pattern to hold on the concrete. The wrapping material may be a water impervious plastic which will affect curing of the cement without the aid of chemical curing agents.