Building new founds inside building using old brick?

[freddiemercurystwin]

I feel silly and ashamed, I shall now take myself of to the naughty step and think about what I have done here tonight.

 

[^woody^]

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

<etc>

If you realised how it works, then you will realise why your proposed method will fail

All foundations will move - initially, then by settlement, and then annually

Your method makes it much easier for tensile and rotational stresses to initiate cracking and then permit a crack to spread along the inherent weak points and junctions of your brick and concrete interface

The strength of properly bonded brick units and flexibility of the mortar is lost. The strength of concrete with suitably sized aggregate and no paths/joints for stresses to take is lost

Its not really just my opinion, its more that fact that your method is one that you have just made up and is not ever used in construction nor ever has been

 

[Mrdjc]

Woody, I see what you mean now, and now that you have put it like that it makes perfect sense.

I have never seen it done before, and I was curious as to WHY it is a bad idea other than "Its a bad idea" answers.

However, I'm still wondering if this really is such a large issue since its a relatively large mass with an evenly distributed static load on it.

If the ground had been disturbed underneath it or it was built half on bedrock and half on sand or something, I could understand it settling differently at each end, instigating tensile stresses.

However, on uniform load bearing ground, I very much doubt it will move to such a degree it will instigate large cracks, the whole mass would move as a whole instead.

If concrete can withstand these stresses alone, why wouldn't it be able to withstand it with the large joints to take up the stresses? It would be like an honeycomb structure.

Underlying point is, IF it moves significantly it is more likely to crack. But will it move to such an extent?

 

[^woody^]

If there is even settlement, and if there is even seasonal movement, and if there are no future ground problems, then you may be OK

But the point is it is a risk and if the ground does not do as expected then the potential for failure is there

Now, the chances and consequences may be minimal, but the risk remains so you meed to decide if it is worth it

I can't see why you can't just use the bricks as a traditional stepped foundation, or lay a concrete strip and then use the bricks - as either way you are using what you have and buying the same amount of concrete in

 

[Mrdjc]

Creating footings ontop of a concrete strip is one way, but I would need to clean up all the bricks completely, and I'd need to mix mortar instead of concrete, which means having to get sharp sand (We have all in ballast)
or alternatively sieving a whole lot of sand!

Not to mention having to make sure that the footings are completely level and straight, and since each brick is slightly different they would have to tweaked individually.. I'm not a bricky, I'm only experienced with breezeblocks and AAC blockwork which is nice and uniform and easy to work with.

Concrete in that sense is magical as you just poor it in and then level it off and job is done, don't need to worry about each and every block being straight or it knocking off the next block to be placed on top.

Still, I appreciate the time you are taking explaining why exactly it is a bad idea. Constructive criticism