Retaining wall?

[Paul.J]

Hope you can help with this.
We have a concrete retaining wall on the side of the house which runs along side next doors side entrance which is about a 40" drop from our back garden.
A lot of the concrete has fell out recently for some reason so needs patching up.
It seems very sandy and dry,so what would be the best way to fix it so the new concrete holds firmly onto the old.
I was thinking of using a mix of ballast,concrete sand and cement which i saw on a DIY programme ages ago saying it was a lot stronger mix,or would just a balast and cement mix do or what do you think??
TIA.

 

[finneyb]

1. Add PVA glue to the concrete mix water
2. Cut back to sound concrete and prime with diluted PVA glue
Proportions should be on the PVA glue eg Unibond container

HTH

Brian

 

[Mcluma]

The reason for breaking could have been that water has entered the concrete and during the winter the frost has done its damage,

is there re-enforcement in the concrete wall? i take it there is not. otherwize it wouldn't break that easy,

I advise to have some steel rods drilled into the top of the wall, this will make the connection between the old and new concrete a whole lot stronger

 

[Graham Orm]

Sounds like it might be more than a patch up job if it's a concrete wall crumbling. Are you sure it's concrete and not rendered brick?

 

[Paul.J]

Thanks for the replies
The wall is i presume as old as the house so 1930s and was fine up until some work was done next door,the house was renovated and nothing was said to me until i noticed it and how bad it was.I have mentioned it to the new neighbours and that i will need to come round and repair it,but from what i can see it isn't brick.I was thinking of banging in some lengths of steel to help hold the new concrete in place??
What sort of mix would be best to use?

 

[Lons]

Thanks for the replies
The wall is i presume as old as the house so 1930s and was fine up until some work was done next door,the house was renovated and nothing was said to me until i noticed it and how bad it was.I have mentioned it to the new neighbours and that i will need to come round and repair it,but from what i can see it isn't brick.I was thinking of banging in some lengths of steel to help hold the new concrete in place??
What sort of mix would be best to use?

Difficult to advise without seeing pics or knowing the size of the problem but...
You should use a mix of 1 part cement / 2 parts sand / 4 parts gravel (I use pea gravel as it's a smoother mix but any clean gravel would be ok). You can also buy a ready mixed sand / gravel mix but I prefer to see what's going in to it.

Do what the others said. Clean away all the loose stuff and wash the dust out. Drill holes into the remaining concrete and knock in some steel rods, 10mm rebar is ideal then paint with pva and concrete making sure it's well tamped. You can put additional re-inforcement into the supporting ground if you wish but I would use 6 or 10mm mesh.
It's important to ensure that the supporting ground or structure is solid and won't loosen or you're wasting your time. Also, if you can borrow a mixer - do so as it produces a much better mix than by hand. the area concerned may not warrant that of course.

Bob

 

[finneyb]

I'm having problems with the idea of drilling into the existing wall - its sandy - you could end up with a demolition job and need a new wall.

How long do you intend to stay in the house? ie do you want a patch-up or is it a new wall now and save work in the future?

After you have cut back to sound concrete you will be able to better see if its a repair job or a new wall.

Brian

 

[Hivenhoe]

Wouldn't it be easier and probably safer in the long run to get someone around to do a proper inspection, given that it's a RETAINING wall? You don't have to follow their advice!

 

[Graham Orm]

Wouldn't it be easier and probably safer in the long run to get someone around to do a proper inspection, given that it's a RETAINING wall? You don't have to follow their advice!

+1

 

[Lons]

Without photos and more info, we're only guessing really!

 

[CHJ]

Paul, you refer to:-

A lot of the concrete has fell out recently for some reason so needs patching up

Do you actually mean just the surface rendering that keeps the rain out and makes it look pretty.

If so then it needs the loose remains brushing off at least and treating with a bonding agent (PVA?) then applying a matching mix to that used originally I.E. it may have been a lime mortar mix as opposed to cement only.

Type "repairing rendered exterior walls" into google for some examples.


Any guidance as to why rendering has failed? is it just old age letting water into the rendering for frost to work on or is there by any chance an increase in water content behind the wall in your garden.

 

[Paul.J]

We did contact a local builder to come and have a look but he didn't turn up,which is not the first time a builder or other trade has done that,but from what i can see from our side the wall isn't bulging as we have the fence panels on top of it and as i say was fine.i will take some piccys when i get round there to have a proper look.

 

[Paul.J]

Paul, you refer to:-

A lot of the concrete has fell out recently for some reason so needs patching up

Do you actually mean just the surface rendering that keeps the rain out and makes it look pretty.

If so then it needs the loose remains brushing off at least and treating with a bonding agent (PVA?) then applying a matching mix to that used originally I.E. it may have been a lime mortar mix as opposed to cement only.

Type "repairing rendered exterior walls" into google for some examples.


Any guidance as to why rendering has failed? is it just old age letting water into the rendering for frost to work on or is there by any chance an increase in water content behind the wall in your garden.

Hi Chas.
No,not the rendering, big lumps have fell out all along the top edge from what i can see.I have had to put a brick under the one slab that was over part of the wall which is the part i am looking at,well that i can see more of.
The builder who worked on next door has cleared the mess up but didn't say anything to me about the wall??
I have looked on Google but didn't find much,nmainly filling cracks?

 

[Graham Orm]

Paul if you want any useable help from here I suggest you post some pictures. Advice on patching it up may be the wrong thing, it sounds to me like it might be a bigger job.

 

[Hivenhoe]

Did the builder use a power washer on it? They appear to create havoc with concrete etc but usually takes several months to see the results.

 

[Paul.J]

I am gonna try and catch em today so i can have a proper look,but have just missed em so will try later and i will get some piccys.
As far as i know no pressure washer was used but some work was been done down the side new slabs layed and new waste pipes put in etc.

 

[Paul.J]

As promised a piccy of the worst bit that has fell out.
Having looked at it now it is all still sold and does look like water may have got in and blown out.
Some of the render is loose so that will come off and re-done.
So what do you think.?

 

[Graham Orm]

As promised a piccy of the worst bit that has fell out.
Having looked at it now it is all still sold and does look like water may have got in and blown out.
Some of the render is loose so that will come off and re-done.
So what do you think.?

Rebuild from scratch. You can patch it if you like but I think it'll just move again. It looks to me like the pressure from the ground behind it along with frost damage...and maybe some vibration have made it give. There's no way to patch it, you will have to demolish and re build. Sorry to be the barer of bad news.

 

[Paul.J]

Yes it is a lot worse than what i first thought and have just had a fellow forum member pop in and have a look and he said what you say.the rest of the wall though is sound all along.
When the builders were here they had the mini digger banging the bucket into the ground for some reason back and front gardens and we could feel the vibration through the house so perhaps thats what caused it??

 

[Hivenhoe]

It may be worth contacting your insurance company?