Rawlbolts?

savagethegoat

I need to drill three holes into my tarmac drive to bolt down an item. Will rawlbolts be sufficient or would I be better to excavate out a square and concrete them in? They won't be under any load.

Luckysasha

Problem with Tarmac is its soft and rawlbolts need to expand to grip the inside of the hole to work properly. It really depends on what your bolting down ie: is it top heavy etc. I personally wouldn't rawlbolt anything to tarmac. You could drill a larger diameter hole and epoxy the bolts in that might be one way around it. I'd imagine a chemical anchor is your best bet but as its only 3 holes could prove costly

savagethegoat

it's not top heavy really...it's a security post. I think I'll chop out a square and set the bolt in a big ball of concrete. Should be easy enough

nmg_ire

def chop out a square and pour some concrete, Tar isnt really suitable for any type of fixing.
You can also get a dye to turn the concrete black so it doesn't stand out.

wiz569

But wont the square of concrete still be surrounded by tarmac, therefore making it as secure/insecure as a rawlbolt in tarmac?

Bruthal

wiz569 wrote: »

But wont the square of concrete still be surrounded by tarmac, therefore making it as secure/insecure as a rawlbolt in tarmac?

Not really. The small surface area around a rawlbolt will mean it wont work very well in tarmac.

The hole for the concrete should be made a decent bit deeper than the thickness of the tarmac as well.

savagethegoat

i'll undercut the sides too and go deeper than the tarmac is.

I guess I'll make up a template for the boltheads to keep them spaced right.

wiz569

Bruthal wrote: »

Not really. The small surface area around a rawlbolt will mean it wont work very well in tarmac.

The hole for the concrete should be made a decent bit deeper than the thickness of the tarmac as well.

I agree about the rawlbolt but unless the concrete is sunk a good bit deeper,as you suggest, I dont think it would be much more secure

iano.p

Definitely cut out the tar and pour in concrete leave it about half inch under the surrounding tar. When it's dry top it off with a bit of tar can be got in hardware shop. It will look a lot better job and the bolts have all the support of the concrete

savagethegoat

it's not in a visually sensitive area fortunately

whizbang

Just use some threaded rod if you are pouring concrete.

I would leave the concrete visible;
I suspect the visual effect of heavy looking bolts in concrete will be as much of a deterrent as anything else.