Has anybody got any experience of putting chemical bolts into a cavity wall. I need to put a few M8 studs into a cavity block wall. I can see that you can buy sleeves to help retain the cement into the correct place but it looks like I need to drill something like a 16mm hole for an M8 stud which seems a bit extreme is this correct. If it was a solid hole the advice I had was just to drill a 9 or 10mm hole for the M8 stud.

I was planning to use this adhesive from screwfix. https://www.screwfix.com/p/easyfix-kem-psc-380-ef-polyester-resin-380ml/1245j

16mm is too big for 8mm studs/threaded bar. I’d be going 12mm. The key to any resin application is blowing all the dust out of the holes. Also it would be advisable to try and leave the back of the block in and not to drill right through.

As above.  I have used them in crumbly plaster rather than cavity block wall and they are incredible.  I sized down to the minimum required to get the sleeve in as the blowing out dust tended to make the holes larger in the plaster.  They are pricey but they are now my go-to anywhere that is a bit difficult.   At M8 you might not even need the sleeve

As above make sure hole is well blown out and free from dust, we use Hilti Hit at work it amazing stuff also used thunder bolts that screw into a smaller hole but to be honest better off using an impact wrench to put them
In

I’ve used them on a gun cabinet. 8mm theaded bar into those soft thermolite blocks. Seem to remember 10/12 mm hole. 16mm is for the ground ancor bolts. Police happy with it but personaly recon I would rive them out without to much force.