Fixing Posts to Tarmac with Anchor Bolts

[Teddg]

Hi,

I am wanting to fix some steel posts to my driveway (post and chain fencing). The posts have a 100mm square plate welded to the bottom with holes for 4no bolts (I did think of only having two fixing per post but I understand Tarmac is particularly hard to fix to so the more the better).

Should I be using rubber sleeved anchor bolts? and if so is it a case of drilling into the hardcore (I need to check depth) slotting in the rubber sleeve and then fixing down with the bolt?

If this is the solution does anyone know where I can get hold of these bolts as all I can find online are the metal sleeved anchor bolts? or would these be OK instead of rubber sleeved ones?

If there are any other ways to fix the posts these would be greatly appreciated.

Thanks

Ted

 

[Norcon]

My choice would be diamond core on the tarmac and concrete them in!
Down about 250-300mm.
But then you're posts will probably not facilitate this method.

Diamond blade then on the tarmac then and dig out a 200mm sq hole x 250-300mm deep and fill with concrete. You can set bolts in this when wet or use thunder bolts when set.

 

[noseall]

Do as Norc says, you are pi££ing into the wind trying to fix to 'mac unless you have a decent spec'.

 

[freddiemercurystwin]

These are what you are referring to: http://www.polymax.co.uk/Catalogue ...30_M12x108_Tarmac_Bolt_with_Rubber_Sleeve.htm but as mentioned they're useless for your purpose, they're designed for speed bumps etc, they're silly money too.

 

[Teddg]

Hi all thanks for your comments - if not the quick fix solution I was planning

Thanks for the link to the bolts and with a bit more info I've managed to track some down but they cost about £2.50/each !! (would need 20). - I guess these don't really work from your comments?

I'm considering using Norcon's solution to dig a 200mm square but would I be OK with setting the base plate 50mm below the level of the tarmac and then putting new tarmac over the final 50mm? (the ready made stuff in a bag) - This way I also get to hide the base plate and fixings.

If I've got this right in my head I'll probably have to use thunder bolts when the concrete is set or can I support the plate somehow to stop it sinking in the concrete if casting in bolts?

With either solution what length bolts would you suggest?

As I don't have use of a diamond blade is there another way of breaking out the tarmac? or is it case of having to hire one?

I apologies now for my very basic questions - sorry

Cheers

 

[Thermo]

a diamond blade and a grinder wont set you back much if you buy them. I would also cut teh plates off of the posts so they can easily set into the concrete giving a very strong fixing. no need to worry about the bolts then.

 

[Teddg]

Hi Thermo thanks for the angle grinder info.

Unfortunately I can't set the post in concrete or the overall height would reduce by 250-300mm - This simple idea is looking like a project

 

[Teddg]

Hi all,

Steel Posts have just arrived so it looks like a job for the weekend (if the weather is good).

Just before I make my trip to the local diy can you please let me know if the following will be OK

1) Thinking of getting a 4.5" Angle Grinder - 720w - Will this do the job of cutting the tarmac?

2) Dig out tarmac to 200 x 200 x 250mm deep (I'm guessing it break-ups pretty easy after cutting the perimeter?)

3) Pour concrete to 200mm deep. (How long do I leave before drilling holes - a day?)

4) Drill holes for thunder bolts - Can I get these from the likes of BQ or do I need to order online (are they called something else)? - Also is 60mm about the right length of bolt needed?

5) Top off concrete with 50mm Tarmac (after fixing post) to match existing and cover plate (is this thick enough?)

Norcon suggested that I could possibly set the bolts (I'm guessing any type of bolt) in the concrete (no need to drill). I know I mentioned this before but am I missing the obvious or will the post not sink in the concrete and how do I keep it upright?

Thanks again for all your help - I'll have to post a picture afterwards to prove I managed it

 

[noseall]

The simplest way, as the guys have already pointed out, is to concrete the posts into the ground. Leave the concrete down so that it is deep enough to allow a covering of mac. Job done.

If you must use bolts then make plywood substitute templates and set the bolts into the wet concrete. Once set remove the sub's and fix the posts to the bolts.