If you can insert a small bottlebrush to get out any dust or silt that s on the concrete this will really help ensure patching success.
Patching hole around conduit in concrete wall.
Spray the surface and inside edge of the cinder block hole with enough water to dampen the block but not so much that the water runs down the wall.
The standard method of prelocating a hole in a poured concrete wall is to position a sleeve where the hole is needed.
You want the concrete surface in each hole to be perfectly.
Use a hammer and chisel to remove loose concrete from the hole.
Pack the material in tightly and make sure the cement connects with both the pipe and surrounding wall.
After hearing that i seriously considered just gluing a piece of plywood over it and calling it a day.
The guys at home depot had a lot of fun lamenting the fact that the hole existed to begin with and then suggested that i build a mold on one side of the wall and fill it in with a pour of concrete.
I considered a lot of options.
Also try to flatten out the bottom of the hole to create a stable level surface for the new patching material.
Press hydraulic cement into the hole with a small trowel or putty knife.
If necessary fill the gap in layers of cement to build up the area slowly.