Conventional concrete posts are reinforced. This of course allows the post to take a much higher loading.
However, it seems to me that simple concrete posts made in 4" round moulds might be quite servicable for light duties, where the posts will not be expected to stand up to (for example) being used as a corner post.
Of course this has the advantage that they could be easily cast at home for very little, whereas adding reinforcement is a bit tricky.
Thoughts?
Sticking a metal pole into the mould before casting is hardly tricky. "Homemade" reinforced concrete is used frequently when laying patios and the like, just by the addition of metal poles or meshes.
Christian.
What sort of moulds? 110mm soil pipe? I think that it would be OK as long as the posts were a maximum of (say) 600mm long.
It should be reasonably easy to add re-inforcement, fence posts aren't pre-stressed - they do use a special mix, though. They could then be a bit longer! There's a reason why they're made in the shape they are...
I was thinking of 110, or 150mm, with of course a slit in the side where it can be spread.
Well, spheres would be a lot heavier :)
Hmm. Lots of polyester rope. Got to be an easy way to make post-stressed posts... G
Rebar is cheep, and easy to fit into the middle of the mold, half fill the mild, lie in the rebar, and fill to the top ......
I have seen a sander used on the side of the mold to vibrate all the air out, this also seems a good idea.
Concrete lintels are like a fiver each, so one has to ask why make your own, unless you are looking at hundreds you won't save that much
Rick
The rate I suspect they turn out the posts I suspect that if they thought they could get away without reinforcing they would. ;-)
Mark S.
I'm unclear why reinforcement is problematic. But there are 2 alternatives to solid bar, neither of which are as strong, but still give some extra strength.
1=2E eml 2=2E plastic fibres in the crete mixgalv eml will last awhile before it rusts and breaks the crete apart, ss eml would last indefinitely.
Mildly post stressed should be not too hard if youre wiling to sink 2 heavy posts into the ground and wrap your metal rebar around them with a big iron bar, to get it under tension. Or maybe a big wire tightener plus bending the bar ends into a loop to give a strong attachment.
Even Polyprop rope, though rather crude, would give a bit of tension. In fact it could give enough to keep the post in compression, theres nothing stopping you putting serious tension on rope. I might consider somhow separating the twined ropelets a bit to give more bonding surface, its no use a tensioned rope that just slides out of tension everywhere except the outer edge.
Fibre mix is an easy option, the bundles are about =A32 iirc. It doesnt give as much strength as rebar, but sitll increaese tensile strength substantially.
You planning to attach 2 strips of wood inside the pipes to give fence panel grooves?
One could even turn them into pretty terrazzo posts if one had no life!
NT
Rebar would practically double the price of a post. (AIUI)
I wonder... Small stainless bar (of which I have a few) at the top, cast in. Round smooth circular depression into which another bar fits. Tie rope on, wind up to get tension. Fill depression with more concrete.
Why not, it's all almost easy once you've got the mould done...
In article , Ian Stirling writes
The post would almost certainly snap IME, concrete relies on its bulk for strength, you can reduce the bulk and increase the tensile strength by the addition of reinforcement (rebar or fibres) and playing around with the mix adding polymers etc. Rebar is cheap and easy to put in, you can quite easily make up a pre stressing rig if you feel keen, assuming you don't want too much, you should be able to scrounge some from a site, loads get wasted.
I would price it up Ian, that doesn't sound right, mind you it will also double the price if you have to make the posts again if they break :-)
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