The only way I've had success in sealing this type of leak is with hydraulic cement. You buy it in quart size cans. This will require that you open some space around the pipe as deeply as possible, making sure to get all of the loose pieces out. You mix a small amount at a time and immediately pack it into the space. It will work even with water coming in, in fact it needs some moisture to work properly. It sets up quickly, so you will need to work fast and mix a new batch if your supply sets up before you use it. If the pipe needs replacing, obviously this is the time to do that. When I had my water supply line replaced about 15 years ago, the plumbers used some kind of caulk, but it did not seal very well. I cleaned their caulk out and used the hydraulic cement. It's never even shown any moisture even though there is sometimes water stand outside. Be sure to follow the directions on the can of cement and use heavy rubber gloves, this stuff is loaded with lime, and it will burn your hands without proper protection.