Building new founds inside building using old brick?

[Mrdjc]

Some of you might have seen my project thread/blog.

Existing founds are about 50cm deep, built in 1950's, shuttered concrete, with no rebar reinforcement, and its not subsiding and has stood there for over 60 years with no issues.

Question is, rather than digging a trench and filling it with concrete casting a new found replacing "like for like".

Is it possible to use bricks set in concrete to build up the founds rather than making it pure concrete like a newbuild?

It would save on material, mixing and allow me to put the old bricks to good use.

It *should* add strength to the founds by staggering them

Does this sound like a good idea or a bad idea?

Reasons against would be useful.

I know old buildings have had founds built out of brick and mortar on a bed of mortar
Just wondered what the take is on using brick with a few cm of concrete between, then another course of brick staggered.

 

[Static]

Bricks are weaker than concrete they also absorb water like a sponge so may be subject to brittle frost fracture..

All round not advisable

 

[noseall]

Put the old bricks to good use by selling them to a reclamation yard and use the money to mass fill with concrete.

Otherwise, if the bricks are tat, break them up and use them as trench back-fill or hard core infill.

Your concrete/brick sandwich sounds bonkers. Why mess about trying to penny pinch at such an important and irreversible part of a build.

 

[Mrdjc]

They don't do reclamation yards here. There's piles and piles of the things all over people's backyards, cheaper and easier to use block-work which has a far better insulation value and is easier to work with.

It would simply allow me to use the old bricks for something useful.

The bricks would be encased in concrete, and in the ground below the damp proof layer. Its inside the building, none of them would be on the perimeter so frost would not be an issue either (especially since they are IN the ground, not exposed to air.)

Old houses used to have their whole foundations built out of brick and mortar on a solid layer of hardcore.

Only difference is this wouldn't be a conventional brick footing, it would be a mix of concrete with bricks inside it.

Any real reasons why It should not be done other than it sounding bonkers to you (Eating raw fish sounds bonkers to me, but the japs do it..)

Take a look at laminate engineered beams, they are weak materials, but combined in the right method are extremely strong.

I know it is fine to use either pure brickwall or pure concrete, I'm just curious if there is a reason the two should not be combined together?

 

[Mrdjc]

This is what I meant:

Untitled

• Mrdjc
• 3 Feb 2012
• 1

Layers of brick buried in concrete.

 

[noseall]

Dig a trench, lay 225mm of concrete then build a mortar and brick wall straight off the concrete and up to dpc and use your bricks this way.

Why faff about with the concrete sandwich as it is both very time consuming and pointless.

 

[Mrdjc]

Because the bricks aren't all the same, they would require cleaning up first, I'd require mortar, and it would all have to be built up straight course by course. This would be very time consuming..

Trench, layer of concrete, bricks, layer of concrete, bricks layer of concrete with adequate spacing between the bricks and capping off completely around each brick will create a level foundation, without the need to clean each and every brick up and lay it completely level.

I don't think its time consuming or pointless, it will save on material, save on labour and save on having to remove the bricks off site.

Other than a difference of opinion, is there any reason why they should NOT be mixed like this?

 

[noseall]

Save on labour! ???

Next you'll be asking how to best to remove and straighten nails pulled from old timber....

It sounds as though you are harking back from the 1940's.

 

[^woody^]

This is what I meant:

Untitled

• Mrdjc
• 3 Feb 2012
• 1

Layers of brick buried in concrete.

No that's a stupid idea .... it will crack and settle.

Either do it in all bricks, bonded and stepped like they did in the middle ages, or use concrete.

And stay off the vodka

 

[Mrdjc]

Why do you think it will crack?
Why do you think it would settle any more than an pure concrete or pure brick footing would?

Do you know it will from experience or are you just taking a wild guess?
Do you have any source to confirm this?

Both materials used separately have been used for yonks in construction, why do you think if they are combined in layers it will suddenly all go amiss?

What's the difference between combining shuttering blocks and concrete and combining these bricks and concrete?

C20 concrete and common house hold bricks have roughly the same compressive strength, once cured it will act as one solid mass.

Are there any SCIENTIFIC reasons for not doing this other than "oooooh", "aaaah" and "Boogey boogey boogey!"

You are perfectly entitled to think its a stupid idea, It would just be nice if there was a reason for your opinion, which was explained.

Hell, I don't like high heels, I don't see the point in them, yet people continue to wear them despite me telling them I think its a stupid idea.


Yes, save on labour.

1. Knock render off old wall
2. Knock old wall down
3. Remove bricks from working area one by one.
4. Dig trench and take spoil outside
5. Clean up bricks one by one
6. Store bricks somewhere and carry them there
7. Pour concrete footing slab and wait for it to dry before building on it
8. Move bricks back to area to be built
9. Mix up mortar and build up every course one by one making sure its level.
10. Wait for it all to dry before continuing blockwork wall.

or.

1, 2, 3, 4

5. Pour concrete layer, add brick layer, pour more concrete over it, add another brick layer
6. wait for everything to dry and cure, then continue blockwork wall.

No moving and cleaning of bricks
Or alternatively moving and disposing of bricks

No waiting for concrete to cure before being able to build footings on it.
No mixing vast quantity of concrete since bricks take up a heap of space.
(Yes, it's mixed in a 150L mixer, by hand..)

 

[freddiemercurystwin]

There have been many sound reasons posted in this thread as to why its a stupid idea, is this you?

 

[Mrdjc]

I could jump on every single thread on this forum and post my opinion.

Opinions are like an *rsehole, everybody has one.

People are stating their opinion along with a reason why they think it might not work.

Frost damage/absorption of water:
It's in the ground, capped with concrete and soil on every side. Normal concrete doesn't suffer from this in founds, existing founds have been there 50+ years.
Absorbtion of water is granted, but concrete also absorbs water, it is below the DPC anyhow.


Bricks are weaker than concrete:
Bricks might not be as strong as concrete, but they are strong enough as footings alone to support a house, so why would they suddenly not be strong enough when used in concrete foundations?

It will crack and settle:
How will it be more prone to cracking than a pure brick or pure concrete mass? Their compressive strengths are similar, and its all tied together using the same concrete. No hairline faults of two different pours of concrete.
How will this settle more than a traditional foundation or slab and footing? The mass is the same, the ground conditions are the same.

If someone came on here and explained exactly WHY it would not work with some kind of information or logic to back it up, fine.

 

[freddiemercurystwin]

Why bother posting if you don't want anyone's opinion, its clearly a conspiracy that we use concrete in foundations nowadays!

 

[^woody^]

I'm on a mobile ATM, so difficult for a long reply, but in the meantime, google for how loads are distributed in bonded masonry and how the gravel functions in concrete.

Then compare how loads will distribute in masonry with big joints and unbonded, and in concrete with large unit ballast and how flexing causes cracks to run around these large units

 

[Mrdjc]

Why bother posting if you don't want anyone's opinion, its clearly a conspiracy that we use concrete in foundations nowadays!

Why bother posting if you have nothing useful to add to the conversation instead of a silly picture and making unnecessary statements?


Woody, I realise how concrete "works", I also know how compressive forces and loads are distributed through materials.

For it to fail, it would need a point load to cause it to fail, the weakest component would loose its adhesive strength and it would part company creating a crack.

Rather than lots of microscopic cracks in the concrete between the aggregate and cement that holds it one massive crack would be created in the brick. (they hate tensile stress).

Point is, its layered and its staggered AND the joints should have plenty of space to allow for flexing (if any occurred)

I quite frankly don't see how a foundation on load bearing ground of these dimensions would suddenly decide that one corner wants to move up or down all of a sudden, or get a huge point load right in the middle of it which is strong enough to deflect the lump to the point it would crack.

The Mortar in masonry usually has a compressive strength a lot lower than the brick it is holding together. Meaning that the mortar "gives" so the bricks do not crack and the wall can flex lightly if required.

This lump, would be very much solid with "zero" give, but that's what a foundation is meant to be, no?