Hi all,
I use postcrete for setting in posts etc. My own feeling is that it would be stronger if I mixed in some gravel (ballast). I've tried it and it works fine - goes off almost as quickly, but I don't know if this is strengthening it or not. Anybody know if this is worth doing or not.
Many thanks,
Neil
The postfix stuff I have used in the past has already had gravel in it.
My feeling is that all forms of postcrete and even halfway properly made concrete are so massively over the top in terms of strength in this application, there is no point.
(A while ago I posted that I had used half a bag of quite old postcrete and it had set like granite. Stuff in good condition is likely to be even stronger.)
The only reason I can see to add gravel/stones/whatever would be when trying to be a cheapskate and extending one bag to fill several holes.
It's probably formulated ideally for what it's intended. Are you having problems with it cracking/failing?
Making up your own concrete in a mixer and vibrating it in situ would probably considerably strengthen it, but I wouldn't bother unless it was necessary.
The advice I had from the fencing company was "dig your holes as deep as possible, and aim to have a big lump of concrete down the bottom".
Worked fine for my 2m tall fences in an extremely windswept fenland location - still perfectly vertical several years later.
Ah, only used the postfix stuff from B&Q. Put two separate fences up using it and have never had any problems.
No not this stuff
It just seems to me that proper concrete has gravel in, so why doesn't this stuff need it as well.
>
I'm just comparing it to ordinary concrete and wonder why it doesn't need gravel when ordinary concrete does. If it would make it stronger than I'd mix some in.
I've heard it said that 10 gravel to 1 cement is a good mix. Some strength, but also some permeability so that water cannot get trapped next to the timber. Also makes it easier to dig out when replacing the post.
I have used both forms of postcrete (though I'd guess that is a trade mark of some sort). Both worked. (Only a few holes - I don't have 'industrial' level experience!)
My feeling is that the sort without stones is a way of using up fines from quarries/beds which are not suited to other uses for some reason. Further, I'd hazard a guess that they have adjusted the mixture to be as cheap as possible to make whilst retaining effectiveness. Either will end up extremely hard and strong by the time it has fully cured.
I would not expect adding anything [1] to be helpful except, as already stated, in allowing a bag to fill more holes. The last lot I used expressly suggested putting broken bricks, etc. into the hole for larger posts so that the claimed posts per bag could be achieved for any size post and hole.
[1] I guess water is needed. :-)
I'll second this. And might I add, that you should also paint the ends of wooden posts with liberal amounts of liquid bitumen, at least up to ground level. This helps prevent water penetration into the timber, so you posts last years and years longer than having them stuck in the ground with no protection.
If this PostCrete stuff is cheaper than making you own Sand Cement Ballast Mix, then go for it. But I always a good mix of the above never lets me down. I might give these new fangled things a try one day, if I feel brave. :-)
The stuff the OP is on about (IIRC) has a big advantage over mixing your own.. you dig a hole, drop the post in and fill it with the mix dry. You pour in water and it sets in about 20 mins. By the time you have had your tea break you can fit the panels. I have used it and it is really good if you are in a hurry.
I can see the advantages in its use, but I think the old ways are still best. Yes, I probably should get more "with it". :-)
We still dig the holes. Set the posts to the levels we want. Support the posts with timber struts. Fix the panels Etc. Make sure everything is the way it should be. Then we mix our batches and pour the 'Crete in the holes.
Doing the posts individually takes forever. Isn't it best to build your fence, then fix the posts in place at the end. Our fences, around the several out-buildings we have had to create, are still standing after, roughly, twenty years. The only things we've had to replace is the gate hinges and a few padlocks.
Ah well. Each tae thir ane, as they say.
I see the question as highly dependent on numbers.
For one or two posts it is much easier and cheaper to get a bag of postcrete. After all, by the time you have bought a bag of cement, let alone the ballast, it has cost as much.
For a few more, it is probably considerably cheaper to mix your own.
For lots, maybe the labour of mixing, or cost of a mixer, outweighs the extra cost? And there might be a discount on a quantity purchase.
Having materials lying around (effectively free), or going to waste because they are surplus, are significant factors in choosing.
The end quality should also be considered, in any kind of job. If you have the time to maintain the work after installation, then, by all means, go with the flow. If you fit and forget, then it's always best to take the time, and maybe spend just a little more, to do the thing properly so it lasts.
I notice that a lot of confidence is now put into these newer products, but do they do the job to last the rigors of time? If they are meant for the quick DIYer to make it look pretty in a short space of time, will the job actually last the full lifetime guarantee period?
I personally hate the quick fix mentality that has been forced into the DIY market. A proper job, to me in any case, is one where the installation is still there, and still looking as good as when it was installed, when I pass by in ten or twenty years time.
A coat of paint or tighten with a spanner to keep it looking good, is all it should need. Most DIY Stores now sell ready made mixtures of most products, and at a much cheaper cost. I have seen half bags of sand and cement for, literally, pennies, and small bags of ballast gravel to mix with them at a couple of quid a bag.
I'm not the type to go back and forth to maintain things. It takes a major disaster to destroy anything I install. So the job should be done properly, right from the design stage, before I will tackle it. Any job can be done with a little thought before hands-on. Most DIYers will tackle a job with great gusto at the start, then find that a little bit of preparation would have done the work quicker, and sometimes cheaper, if they had looked before going ahead.
Once your fence posts are fixed, that should be them finished. If you have to make adjustments after you have poured the ballast, then you are making the job weaker than it could / should have been. That goes for one or many posts. If you make fencing without fixing the posts first, any adjustments can be sorted before the posts are fixed in their final positions.
Leveling and straightening should all be done without the posts being fixed. Holding the posts in place with small battens of timber, or metal struts, then fixing your filler panels, or whatever, in between, allows you to make all the small adjustments that make the fence look great. Once everything is in place, then you make your mix and fix your posts in their final positions.
If you want to use PostCrete to fix the posts in their final positions, then all good and well. But, in my opinion, don't fix the posts until you know the fence is going to look the part, and is going to last the years you want it to.
But that's just me. :-) Rant over. LOL
The fence and gate at the side of my house is fixed in Postcrete. It's been there at least 10 years, probably nearer 15, and it looks like the concrete (and post) are easily going to outlast the hazel wattle panels.
Concrete, ie with stones, is indeed stronger than cement mortar. So you can mix stone in no worries. Not that fence post fixing needs a lot of strength. In fact sometimes people use ballast alone, no cement.
NT
Ditto!
Ret
Not having a go here, but I wouldn't back your gut feeling against the knowledge & experience of Lafarge/Blue Circle & Hanson Aggregates. If it needed it, they would put it in.
There are two types, one is just a fine powder, the other has aggregate. Both seem to work, in fact I reckong the former is better.
Virtually any mix will set posts, so bagged ready mixed is just a question of whats cheapest plus accelerator. Maybe they bought a huge pile of slate dust for 50p.
NT
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