Setting Wooden Gatepost in Concrete next to a Brick Pillar

[RonK]

I have a 175 mm square wooden post that I am setting in a hole as shown in the really not to scale picture below!! The hole width is 175 mm from each side of the post except for the side that faces the brick pillar. The width of the hole here is 20mm.

Can I just pour concrete into the hole right up to the brick pillar, i.e. fill the 20mm gap, or do I need to leave some room for expansion/contraction of the concrete? This will be really hard to do obviously as the gap is only 20mm.

Is it OK to entomb that one side of the brick pillar foundation in concrete? I'm thinking of putting some masonry bolts into the brick foundation to allow the concrete something to bond to. Obviously only the heads of the masonry bolts will be showing as the gap is only 20mm. I'm not sure how much this will achieve though - a poor version of rebar is my thinking here.

An added complication is that the pillar is very unstable so will need to come down soon. I need the gatepost in even sooner otherwise I'd rebuild the pillar first. I'm assuming so long as the underground foundation bricks are sound I can leave these in place and rebuild the pillar on top of them? Obviously 1 side of these foundation bricks will potentially be encased in concrete.

Thanks,
Rich.

 

[jj4091]

What are you going to be fixing to the post? Bricks and concrete will probably expand/contract at the same rate especially underground. When you are ready can you just take the pillar down to ground level and use the base as a footing, ie is it hollow or reinforced with concrete and re-bar.

 

[RonK]

There are 2 posts - one already in place and the one we are talking about. The one already in place has a large gate attached to it. The one we are talking about will have a small gate attached to it. When the gates are closed they are joined together by a throw over loop.

The post I am putting in is a replacement for one that rotted. The original post was just concreted in with the 20 mm gap fully concreted. The post was not tied into the pillar anywhere apart from the concrete base.

The pillar doesn't have a concrete and rebar core - I'm not too worried about that at the moment - when I come to rebuild it I will probably add concrete and rebar.

I am planning to reuse the underground brick footings - yes. Again I can always strengthen them with concrete and rebar.

It sounds like I should be fine just filling the hole with concrete and not worrying about expansion/contraction?

Thanks,
Rich.

 

[jj4091]

Yes you should be fine with just a small single gate fastened to it but when you come to rebuild the pillar build some right angle brackets into the pillar that you can screw to the posts. Stainless steel will be the best choice as there is going to be a gap in which part of the brackets would be exposed to the weather and galvanised would just rust away over time.
Yes no prob about exp/ cont..

 

[RonK]

One question - even though the brick and concrete expand the same what do they expand into? This is why i was questioning an expansion gap/joint. As the concrete cures it will shrink slightly so shouldn't be an issue but I'm asking more to satisfy my curiosity really!

Thanks for all your help,
Rich.