Postcrete - whether to mix in agrigate or not?

[Neil]

Thanks for all the replies folks. This thread's got so long I'm not sure where to place this conclusion, so I'm putting it here :)

Loads of good advice and different approaches here. The original question was whether or not to add aggregate to Postcrete, and it seems obvious to me now that if it needed it, then the manufacturers would have included it. So I'm happy to accept that.

However the discussion on whether to use the stuff in place of the cement/concrete mix is also interesting helps me at least make some decisions for the future on how/when to use each. I think for myself I see both the use of the fast-mix types have a place just as the old concrete does, but as somebody else (lost who said it now) said it is a question of quantity for me. If all I need to do is plane a few perhaps short posts then the quick-mix stuff is really handy. Alternatively if I want to dig in a line of fence posts then as BigWallop advises I think his method is best and probably a good deal more economic.

All good stuff guys - many thanks. Neil

[mike]

Postcrete is an expensive way to go if you're doing a long run. Much cheaper to mix concrete and add a dash of rapid hardener.

[Bruce]

That's a valid point, however concrete is not as good at filling small gaps. The aggregate tends to bridge them and prevent the concrete falling into them.

Since postcrete is essentially a gap filler, the absence of aggregate is actually a good thing. However, for almost all other applications, the inclusion of aggregate makes for a much better job.

[Dennis the Menace]

I'm going to try doing some post and rail, without putting the posts in first, I'll keep you posted!

[harryagain]

Posts last longest in the metal post spikes. Also quicker to erect. Any form of burial leads to rot in a few years especially now the treament on the timber is such crap. ie no arsenic/copper allowed any more.

[Chris Hogg]

Much depends on the subsoil, and where you live. Our top-soil is shallow, and gets very stony deeper than say 8" and with some quite big stones, so it's difficult to drive Metposts in and keep them straight. I set some fence posts in Postcrete nearly 15 years ago, and they're still fine. No additional aggregate, BTW, there was plenty in it already. Within that time, the council put up a post and rail fence along a roadside verge nearby, using Metposts. They disintegrated within a few years; we are by the sea and have a lot of salt in the air. If stainless or heavy galvanised Metposts were available, they might be OK, if they could be driven in straight.

[Andrew Gabriel]

I put some in 30 years ago, and they're still fine. The make was Fensock which no longer exists AFAIK, and they were better quality than the Meta make today.