Reinforcing fence post with cement

[Widget1983]

Hi guys.

We have an older timber fence which has started falling down. Few days ago we got some strong winds that pushed the fence over. I purchased a bag for quick-set cement from Bunnings, I wanted to reinforce the posts until we can have the fence fixed/replaced. I just read the bag and it says 1x 20kg bag = 0.01m3. This confuses me. Isn't 0.01m3 the same as 1cm x 1cm x 1cm ? That doesn't sound right.

I was originally planning on using 1/2 bag (10kg) for one post and the other half for a 2nd post. Perhaps I've misunderstood how cement works & the amount I can get from each bag? I'm not sure how much I would need for it to be sufficient at supporting each post.

Thoughts?

[rambunctious]

I am not a mathamatician (spellin) but that means 100 bags to one cu metre
Have a look here https://www.bunnings.com.au/easy-mix-20kg-rapid-set-concrete_p0760445

[Widget1983]

I am not a mathamatician (spellin) but that means 100 bags to one cu metre
Have a look here https://www.bunnings.com.au/easy-mix-20kg-rapid-set-concrete_p0760445

ya, bag says 100x bags = 1m3 (100cm x 100cm x 100cm) but wouldn't that mean 1x bag = 1cm x 1cm x 1cm ? I'm confused by this.

The link didn't work (404 error). This is the concrete I picked up https://www.bunnings.com.au/bastion-20kg-quik-set-concrete_p0760335

[ErrolFlynn]

100cm x 100cm x 100cm = 1,000,000 cubic cm
Divide 1,000,000 by 100 and it gives 10,000 cubic cm
The cubed root of 10,000 is about 21.5 cm

So, the bag of concrete mix would fill a box with dimensions of 21.5cm x 21.5cm x 21.5cm.

[droog]

ya, bag says 100x bags = 1m3 (100cm x 100cm x 100cm) but wouldn't that mean 1x bag = 1cm x 1cm x 1cm ?

0.01m3 is 1 one hundredth of 1m3
1m3 is a volume of 100cm x 100cm x 100cm

Divide the volume by 100 only once, ie = 100cm x 100cm x1cm
You are dividing all three directions by 100.


And why did the fence fall down ? wind force ? soft soil ? rotting ? etc
I suspect one bag of cement will do very little to help, I would be buying a couple of long star pickets and driving them down beside the post as deep as you can, then screw the post to it.

[mic-d]

1cm x 1cm x1cm = 0.01m x 0.01m x 0.01m = 0.000001m^3 not 0.01m^3

I would do what Droog suggests and use star pickets. 10kg of concrete won’t do, particularly if the posts are rotted.

And Droog, are you a fan of Clan of the Cave Bear books?:)

[droog]

And Droog, are you a fan of Clan of the Cave Bear books?:)

No, more Clockwork Orange.��

[mic-d]

No, more Clockwork Orange.��

gotcha

[Widget1983]

And why did the fence fall down ? wind force ? soft soil ? rotting ? etc
I suspect one bag of cement will do very little to help, I would be buying a couple of long star pickets and driving them down beside the post as deep as you can, then screw the post to it.



I would do what Droog suggests and use star pickets. 10kg of concrete won’t do, particularly if the posts are rotted.


Thanks guys. I might have to refresh my math a bit, not that it was great to begin with lol.

The fence itself is pretty weathered. The nails are rusting out so the palings are falling off and twisting. The rails are rotting where you can pick away at the wood with your nail, but still has some strength left for now.

Originally that section of fence fell down 45* in one direction. I propped it up with some 2x4 which has worked well for about a year. The other day we had some strong windy days which pushed the fence in the other direction 45* (stopped by a greenhouse). The fence is pretty weathered, I'm not 100% sure on the condition of the posts, but I don't recall seeing rot down at the soil. I suspect deeper down may have rotted away leaving little support for the main part of the fence.

I'll have a look around for a couple of star-pickets. What size should I look at? The fence is 1.8, maybe a 2m picket hammered down 50% ? Would it be worth trying for a second bag, so I bag per post, or still wouldn't be enough ?

[rambunctious]

Thanks guys. I might have to refresh my math a bit, not that it was great to begin with lol.

The fence itself is pretty weathered. The nails are rusting out so the palings are falling off and twisting. The rails are rotting where you can pick away at the wood with your nail, but still has some strength left for now.

Originally that section of fence fell down 45* in one direction. I propped it up with some 2x4 which has worked well for about a year. The other day we had some strong windy days which pushed the fence in the other direction 45* (stopped by a greenhouse). The fence is pretty weathered, I'm not 100% sure on the condition of the posts, but I don't recall seeing rot down at the soil. I suspect deeper down may have rotted away leaving little support for the main part of the fence.

I'll have a look around for a couple of star-pickets. What size should I look at? The fence is 1.8, maybe a 2m picket hammered down 50% ? Would it be worth trying for a second bag, so I bag per post, or still wouldn't be enough ?

https://www.bunnings.com.au/search/products?page=1&q=star+pickets&sort=BoostOrder

Forget the cement.
If the fence has fallen at 45 degrees the rot will be mostly below ground.
Pickets and screws as above then sell the pickets when you have replaced the fence.

edit.. Just as a heads up, if there is good concrete around existing posts you may have trouble getting the star pickets in.

[havabeer69]

https://www.bunnings.com.au/search/products?page=1&q=star+pickets&sort=BoostOrder

Forget the cement.
If the fence has fallen at 45 degrees the rot will be mostly below ground.
Pickets and screws as above then sell the pickets when you have replaced the fence.

edit.. Just as a heads up, if there is good concrete around existing posts you may have trouble getting the star pickets in.

which is why someone invented these

https://www.bunnings.com.au/simpson-strong-tie-90mm-fence-post-repair-and-reinforcement-e-z-mender_p0078506
537590

537591





there's another option of concrete versions, but I'm not sure how available they are in australia
https://tate-fencing.co.uk/product/concrete-repair-spur/

[mic-d]

which is why someone invented these

https://www.bunnings.com.au/simpson-strong-tie-90mm-fence-post-repair-and-reinforcement-e-z-mender_p0078506
537590

537591





there's another option of concrete versions, but I'm not sure how available they are in australia
https://tate-fencing.co.uk/product/concrete-repair-spur/


thanks for this post