For many years under the direction of the ministry paving branch we repaired road potholes successfully with the following technique.
(a) Jack hammer and cut out the road pothole and ensure the hole is tapered with the largest section at the bottom. (Like a plug.)
(b) Heat the hole area with a propane torch and make sure there was no moisture in the new tapered hole.
(c) Apply inside the entire tapered hole and the bottom of the hole a sticky tar material to seal the area and cement in the filler material.
(d) Fill the tapered hole halfway with hot patch mix and tamp the materials with a hydraulic Stanley tamper or equal, then fill the tapered hole with hot patch mix and tamp the materials down tight to seal the surface. Add more materials required to complete a smooth packed and sealed surface at the top of the pothole patch. Add tacky sealant to seal the top of the patch area
Simply putting loose gravel or uncompacted patchmix into a pothole is a waste of time because normally after two or three vehicles cross the uncompacted materials, the materials wind up strewn around on the road surface and the pothole reappears.
Bob Johnson, Nelson