HCl and lime mixture?

I have a pipe that I carved out of stone. A couple days ago it got dropped and snapped in half by someone who was borrowing it. They gave it to one of their friends who fixed it perfectly. It was actually astounding how smooth and perfect the fix was. I only got a few minutes to talk with him and he said to fix it he just mixed powdered lime and muriatic acid and used that to melt the stone together.

When I got home I tried googling this to find out more but havent really been having much luck. As far as I can tell what happened was that the lime was neutralized by the muriatic acid which I assume caused a lot of heat to be given off in the process.

Could someone explain better what exactly happened during this reaction and how I would go about replicating it(ratios) in the future if I ever needed it to fix something like this again?