UKC

Are breeze blocks too friable for expansion bolts able to take 80kg dude on a 7m slackline? If no, any advice on *which* bolts? thanks slackers

In reply to iksander: Are you talking solid concrete blocks or the thermalite sort?

In reply to iksander:

Chemical bolts if it gets too iffy?

In reply to iksander: Make sure it's loaded side-on, i.e. shear rather than pulling straight out. I'd go for a couple of 5" resin bolts.

In reply to iksander:

check Fisher fixings for pull out force.
Your weight, dynamically loading on a straight pull out, is a huge force.

Make a mounting block, and spread the load over 2 or 3 bolts.

Or rig an equalisation system up.

Or get brackets made, that transfer the load 150mm or so away from the fixings, putting more shear on the bolt, rather than straight pull out force.

You could hire a pull out rig from HSS.

Chemical anchors are ok if you don't drill all the way through. If you do, and you can get to the rear, screw a board over to keep the resin in until it sets.

In reply to iksander:
Breeze (or cinder) blocks are appalling things and have a very low compressive strength, they also don´t take fastenings at all well as anyone who´s tried to get a nail to hold in one will testify. To take the load you need (ca, 1000kg) you want at least 3 full depth chemical fastenings spread a long way apart, say 300mm each. But the wall will probably fall down anyway if the load is outwards as walls are only designed to take loads in compression.
In my younger days I had the pleasure of watching a member of HM Forces (fuelled with about 20 pints) kick his way to freedom through a breezeblock toilet wall to escape the attentions of the MP´s which tells me something about their strength (both pissed soldiers and walls)!