Replacing fence posts in retaining wall recess

[silly_savage]

Aye, it's more though of getting it into the channels and behind the post that fills me with dread. The Durapost is an I section and I aim to get this encased as much as possible to avoid voids and bond it to the wall.

Thinking a plan of attack might go something like this:

Mix up a fairly high wet, small aggregate (like grano dust) concrete, yes I know it'll be weak, but more than likely strong enough as we don't require very high compressive strength here.

Fill hole.

Attach a wooden block either side on the post, bottom at 1800mm down.

Ram it home with a rubber mallet (the cross-sectional area is much less than a wooden post so hopefully this should work)

Attached the top of the post to a brace between the two houses

Remove the blocks and tamp & top up at the sides of the post

Reattach base blocks (resting on the wall) to maintain height while the concrete cures.



Of course I might completely ditch this plan after the first one if it doesn't work.

 

[freddiemercurystwin]

You would use a proper flowable grout product like this that you can pour into the void to fill it 100%, you're just making a rod for your own back in not using something that doesn't flow properly or isn't a strong mix. https://www.sealantsandtoolsdirect....eKFeNQWD3SZ3fQ8KI1lwDlNc8BonzQuwaAihkEALw_wcB

 

[stevie888]

Wet mix: you simply cannot guarentee proper hydration otherwise.

 

[silly_savage]

Finally found the time and energy to clear out the holes. Turns out the slots are only 500mm deep so I'll have to trim the 2.4m posts down slightly or have a 1.9m fence.

Borrowed the 4yr old's trowel to get the spoil out from the hole.

 

[silly_savage]

Managed to set a whole one post today. Though I'm hoping it should speed up a bit now I know what I'm doing.

I did end up cutting the post by 100mm in order that they match up with the one my gate is going to close onto when I move it, that's a 1.8m post that will be surface mounted. Have the cut end a little spray with some paint and mixed up about 0.1m² of grano mortar. I used the calculator on paving expert but it seemed a little wet so stopped short of adding all the water, then realised I would be a bit short to totally top out the hole so added the rest of the water and a bit more stone dust/cement.

Handily The posts came in some 150mm cardboard tube so I cut down half sections of this and backfilled with stone dust to keep them in place. The rain last night had softened up the card a bit so it conformed to the wall pretty well.

My plan of whacking the post into the poured mortar worked well, cut straight through it and hit the bottom of the channel with a confirmation thud. I shured the post with a bit of OSB some builders left here and a 2x2 that came from the old fence, jammed between the two houses. All checked out with the laser (I gave up trying to use my cheap Wilko level). It's within a mm or two of dead plumb in both directions.

Even managed to rescue a poor little frog that had managed to fall into the hole. He was a bit dusty but hopefully fine.