Breeze blocks like Thermalite or Celcon are used a lot in the property industry for their ease of use and green credentials. We had a requirement to fix some wall brackets to Thermalite blocks.
The fixings needed to be able to with stand a reasonable amount of weight being hung off them so had to have good structural strength. Thermalite blocks are scratched with a series of lines which indicate the type of block. In this instance the blocks had 6 squiggly scratch marks that designate the fact that they are from the “Turbo” range.
Thermalite blocks are quite brittle and can be easily drilled or cut producing alot of dust when worked. Any fixing into the block needs to create a tight and secure bond with the inside of the drill hole.
The fixings used here contain chemicals so where gloves, eye protection and a mask in order to minimise accidental ingestion or contamination.
This job requires M8 studs so a 10mm hole is drilled into the Thermalite block using an HSS drill bit to a depth of 85mm.
The holes need to be thoroughly cleaned out of all dust created from being drilled. To do this a straw, preferably a metal one to stop the straw walls from collapsing under pressure, was taped to the nozzle of a vacuum cleaner and inserted into the hole with the vacuum cleaner turned on to suck out all the dust. As a belt and braces exercise the inside of the holes was coated with a very quick drying clear concrete sealer and left to dry for 4 hours. This step is not absolutely required.
With the holes prepped to accept the chemical fixings its now time to insert the glass capsules. Make sure the arrow on the capsule is pointing into the hole and push the capsule all the way down to the bottom.
Then place the hex end of the M8 stud into the chuck of a drill and tighten it up. Place the chisel end into the hole up against the end of the glass capsule and start the drill pushing the stud into the capsule until it breaks.
Drill the stud home so that the collar of the stud is just protruding out of the hole and then leave it to set for an hour.
Once the chemical fixing has been allowed to set the bracket can be mounted on the studs and the hex nuts tightened up to secure it.