Using premixed concrete for gate post.

[John Brown]

I have to put up a small gate, around 1m tall by maybe 1
5m. I've dug a hole approximately 900mm deep and plan to use a 100mm square post. Was going to use Postcrete, but reading that it's not recommended for gateposts. Can I use premixed concrete in the same way, i.e. dump it in the hole and add water, or fill the hole with water and add mix?

 

[Robbo3]

Postcrete will be fine. Mine's last over 25 years. If you use concrete you have to wait 24 hours for it to set.
You can get post sleeves which you heat up but if not done properly allows water to collect & speed up rot. Better to paint with bituminous paint 4" to 6" above ground level. I always place a layer of tamped aggregate at the bottom of the hole to allow drainage

 

[John Brown]

Had looked at the Postsaver sleeves, but can't find anywhere to buy individually. Luckily I have some Blackjack somewhere. The 24 hours bit isn't really a big deal as I'm only doing one post.

 

[Robbo3]

Postcrete is quick & easy. Despite what the instructions say, mixing with a stick after watering is beneficial.
Most fencing suppliers sell Post savers.
I have one I can send you if you need it.

 

[MikeJhn]

Postcrete is not a very good concrete mix for a gate, better to get a bag of all in aggregate and a bag of cement and mix your own in a wheelbarrow, a waste of cement for just one post, but I am sure you can find a use for it somewhere else.

 

[John Brown]

Well I already have the postcrete now. Maybe I'll bulk it out with the big pile of rocks that came out of the hole. Would that help?

 

[flying haggis]

if you can break the rocks up a bit so it more resembles aggregate the better

 

[Geoff_S]

Well I already have the postcrete now. Maybe I'll bulk it out with the big pile of rocks that came out of the hole. Would that help?

Not sure that’s going to give you the right ratio of cement to aggregate. It might turn out too weak.

 

[dizjasta]

If you are using timber for the gate support post then the use of concrete as a surround to the post is likely to cause rotting. A concrete surround provides a perfect enclosure around the timber to hold water and encourage timber failure. Your idea of using additional aggregate could be the solution. It may provide a weakened post surround that will allow water lose and preserve the timber a little longer. Good luck.

 

[John Brown]

I chucked the "rocks"(mostly the size of large strawberries) back in, threw in the tail end of a bag of premixed concrete, added a whole bag of postcrete. There was still a fair amount of space at the top, so I went out and got another bag of concrete, and chucked that in. I don't think it's going anywhere.

 

[John Brown]

Oh, and I painted the post with Blackjack 150mm above and below the ground line.

 

[Jameshow]

I chucked the "rocks"(mostly the size of large strawberries) back in, threw in the tail end of a bag of premixed concrete, added a whole bag of postcrete. There was still a fair amount of space at the top, so I went out and got another bag of concrete, and chucked that in. I don't think it's going anywhere.

Postcrete imho goes off pretty quickly and is quite a rich concrete and isn't harmed by throwing a few stones in in the midst of it.
I usually water before, half way down and at the top to be sure its fully wetted out...