Epoxy Concrete Repair?

[xd400]

Hi All,

Have block and brick house with smooth concrete render. Have replaced windows with UPVC but need to pack the concrete render corners out a bit to make good. Previously bodged with wooden windows placed in.

Now I can either grind back the corners completely a few inches and use external beading & render up or was thinking of using this epoxy concrete repair you can buy. Anyone used it? How manageable is it - ease of use/mess? Was thinking of using two trowel system to make good the edges.

 

[Blagard]

It sounds as if this is a small job of making good the render. Remove all loose, prime the surface with thinned PVA and re-render using a plastering sand cement mix. Do not make the mistake of using building sand. Avoid doing the work on a hot day with the sun beating down on it as you want the water in the mix to stay there until it is set.

 

[xd400]

Thanks for the reply. It's not so much making good as packing it out and squaring it up. The existing corner is fairly flat, angled in and intact so I'm concerned it won't give a decent key for new concrete to hold onto

 

[Blagard]

OK, I have used epoxy mortar a couple of times and it is very expensive, but will do the job. You must work accurately with it as it can be difficult to remove if smeared onto surfaces unintended. It may only be the product that I used but the aggregate particles in it mean you cannot feather it out cleanly. It would be better to cut a step into the item to be repaired to mark the extent of the epoxy to be applied so it can be finished flush by abutting the step. Speed is another factor, make sure you can apply it in the timescale for setting, so for a big repair it may be best to build out almost to finished level so a final thinner layer can be applied later.

 

[^woody^]

Use normal render mix and add SBR. That will be as good as epoxy but much more workable.