Steel gate posts 120mm square. Need to be buried 700mm in ground. Concreted in.
What concrete to specify (ready mix)?

Would 40N be inappropriate?

Postcrete?

20 minutes ago, WWilts said:

Would 40N be inappropriate?

you don't need anything special, so forget 40N.

neither do you need readymix unless there are several m3.

 

yes to postcrete, or any diy mix.

Basic 1:2:3 mix would do the job (roughly 20n.) It's probably only a couple mixers worth.

5:1 here with integral waterproofer added around 100mm steel posts.

With pieces of metal welded to the parts of the post that will be in concrete to give extra strength.

16 minutes ago, TonyT said:

pieces of metal welded to the parts of the post that will be in concrete

Tangs.

Your welcome 

15 hours ago, saveasteading said:

you don't need anything special, so forget 40N.

neither do you need readymix unless there are several m3.

 

yes to postcrete, or any diy mix.

Each steel post will have to withstand the weight of a >50kg heavy driveway gate leaf, 1640mm wide and tongue&groove construction (sail effect in gales). 

That's why considered strong concrete approx 450 x 500mm & depth 700mm. With additional resistance to deflection of post using buried 500mm rebar rods in tripod configuration, to act as buttresses. (plan view attached)

Would something other than 40N concrete do the job better? (approx 0.7 cum concrete for 2 driveway gateposts).
And is dpm lining of the hole advisable to reduce rapid drying and shrinkage of the concrete?

Edited September 27, 20233 yr by WWilts

Forget the readymix, just a couple of tonne bags of ballast and 12 cement needed.

 

How is the rebar fixed to the posts?  Make sure it is 32 or 40mm.

 

Ducting between posts for automation.

 

Be good if the posts were galv.

Tks to all. Done the deed in half hour, with 40N readymix after all. Labourer could go on to other tasks, which helps claw back some of the readymix cost.

 

Thin rebar buried without fixing to posts, just to reduce the risk of concrete buttresses cracking. Yes, ducting embedded in concrete to facilitate automation later.

Ditched the dpm idea as being further overkill.

Will report following gale.

Edited September 27, 20233 yr by WWilts