We have these blocks https://www.bradstone.com/products/countrystone/ and I have used them around a patch of artificial grass as and edge (1 block deep). Some of them have failed and I suspect it is because of the thaw freeze cycle. I've replaced the ones that went and I'm looking to put a sealer on them to try and stop this, or at least reduce it, from happening. Any suggestions on a sealer? They're a bit damp at them moment since it's now autumn and has been raining a fair bit so something that is breathable would be good so I don's seal a load of water in them.
Cheers