I have built many fences over the years and tried a bunch of different ways and finally settled on a compromise between the firm anchoring of concrete versus the permeability of crushed rock (20mm or 3/4" crush) to set posts.
I get a yard or two of 3/4" (20mm) road crush. I buy a couple bags of straight portland cement (not concrete mix but cement).
The proper ratio (shovel fulls is 3/1 assuming you are mixing conventional concrete) - I end up using 4/1 mix so it's not quite concrete but also is more bonded compared to straight gravel/aggregate.
Here's the drill;
I set the posts deep to at least the frost line (48") and sometimes will go 60" or more if the soil is not suitable (soft). Corners I always go 60"+
I dry pack the mix a couple shovels to half a wheelbarrow at a time and just pound it all the way around using a 2x4. My line levels are set up and I use a level for the other direction as I'm doing it periodically.
Basically I shovel from the pile of crush and shovel a scoop of portland cement with a 4/1 ratio and fill the wheelbarrow and then bring her over the hole for packing and setting DRY.
My theory is this provides some bonding to the aggregate, yet does not fill all the inclusions (holes) - so it ends up being permeable to water, yet the added cement binds the mix as I pack it in the hole DRY, a half wheelbarrow at a time, until I reach my desired depth - usually just at grade.
I double check my post alignments with a lazer at a few points after setting and packing my posts. A 2x4 can pack one side of the post easily and bring the post "over" to alignment quite a bit more than you would expect.
Once They are all packed tight and in perfect alignment - I run the water slow into the holes and allow the water to saturate.
I end up with solid posts, proper drainage and lazer straight posts that seem to last decades. Did my mom's place in the late 90's and the posts are still rock solid - even in wet areas of her yard.
Did another half dozen fencing jobs for myself and probably just as many to that in addition helping friends out as well. All great results with zero issue.
It's also way easier - doesn't need bracing - isn't a pain to mix concrete - and goes surprisingly fast.
|