Butt jointed timber epoxy connection

[Greenalleycat]

This one coming at you from the wonderful world of DIY
I've put a 125sq post in for my (low) retaining wall, don't like it, and wish I'd used a 150mm square post to match some others I put in previously

The problem is, it's concreted 600mm into the ground and I don't feel like pulling it out
I've come up with the genius idea of cutting the 125mm off, epoxying a rod into the stump, coating the face with epoxy, and sticking a 150mm on the top
I am looking for any thoughts or advice on how we can make this connection better - any good way to improve the interface between the two timbers etc

I am NOT looking for someone to tell me this is a stupid idea and I should dig the post out
Give me some credit that I've spent a bit of time thinking about this, and haven't given all the details that have led me to this solution
This is just meant to be a semi-serious lighthearted post to get any ideas I can use to improve the solution

 

[Tomfh]

This is a stupid idea! You should dig it out!

Now that's out of the way. What is the finish you are trying to achieve? If it's simply too small I'd be more inclined to enlarge the post with new cover plates.

But yes, you can embed a post (or some heavy dowel), and sleeve the new post on top. It will need to be well sealed or it will rot out quickly.

 

[Greenalleycat]

The thing is tied at the top and has 'rails' each side so this is basically just a shear connection in the primary overturning direction only
Sideways the rails buttress it, and the tie at the top means we don't need a moment connection

The finish needs to be a) durable and b) not slop around so that we can finish building the wall
The sealing/rotting is a concern that I have - that's where we are hoping the epoxy on the end grain will help
I will also probably chip out a bit of concrete/dirt around the post and pour another bag around it, just to provide a bit of protection


...I am also talking to a friend who deals with diggers to see if I can get a digger dropped off for free
Anyone know how easy it is to pull out a post embedded 600mm below ground? What size digger would we need?

 

[Tomfh]

If you really coat it well with epoxy, and fully plug up the holes, it will be ok. Note that when you cut treated timber, the cut faces are not treated, so you really need to protect them well.

If you don't need moment connection then it's a lot easier. Those 150mm/200mm long bugles are great for landscaping connections.

A 600mm post will come out pretty easy. I've pulled many stumps and similar embedded objects with my towbar, and failing that, with a chainblock attached to a tree.

 

[Greenalleycat]

We've been treating most of our cut ends (I say most as occasionally I forget...)
I am nervous to put protection on the post ends in this instance though as I imagine it will interfere with the epoxy bond
I've got some 16mm rod that we are planning to epoxy at the junction for the 'structural' aspect of the connection

I wanted to pull the thing out but the Chief Stakeholder in Charge thought that was ridiculous
Cutting the existing post off was considered an acceptable compromise....

 

[Tomfh]

By protection I meant the epoxy in this instance. Epoxy soaked wood is pretty robust. I use it in marine settings.

Do you have thicker epoxy for the rod?