I had made a stone cave and used silicone to hold it together but it kept falling apart so I went looking for something better "again" I found a new product by J-B Weld called Water Weld. It is drinking water safe! I didn't know how well it would work with limestone because it absorbs water. I waited till I knew it would hold together before posting this. It has been in the tank 24 hrs and holding strong. You can actually use it under water to patch holes in boats water tanks etc. Ok now the pictures. This it what it looks like. Its a putty epoxy.
Cut off a small chunk and kneed with your fingers. I wore rubber gloves. Clean your knife!
I used a grinder to make the stone as flat as I could and shaped the putty into a rope and joined the stone together. Pressing it as hard as I could to fill all the gaps. It has a set time of 15 -25 min and is fully cured in 1 hour.
This is what I came up with. The epoxy is so strong I can pick up the whole thing by the top stone. It is real heavy! Finally a great epoxy to use on underwater features. Hope this build was helpful.
