How much does a normal cement screed expand with moisture Ingress?

[hetgen]

Hi all, Please see the clip below.

The wall is a shotcrete wall with an EPS core and doesn't have much shear strength, so I'm not saying the wall will contain the screed if it expands, but my question is how far does a screed expand per linear
length?

Does floor screed expand enough with moisture ingress to cause such damage on a perimeter wall?

Many thanks.

 

[jayrod12]

Generally concrete shrinks while curing unless specifically designed not to.

It would expand with increase in temperatures.

 

[HTURKAK]

The floor screed will expand with moisture ingress but may cause just hair crack on the perimeter wall specially in case of floating screed..

 

[hetgen]

@HTURKAK

The floor screed is supported on a 200mm thick non-structural ultra-light polystyrene concrete which in turn is supported on a concrete flat slab.

There is no underfloor heating that could cause temperature increase, that is why I'm suspecting moisture ingress, but the expansion seems excessive.

 

[Ron]

As jayrod12 noted, shrinkage is more likely.'
In general, concrete volume is highest at the time of placement and never returns to that volume, even with thermal movement. The only exception is long, narrow strips of concrete (sidewalks, pavements), which can expand thermally, enough to buckle the concrete.

 

[hetgen]

Thanks, all.

I agree with you all, I have to check elsewhere to find the culprit, the screed is not the one doing this.

 

[HTURKAK]

Eng.HETGEN,

I do not look to web everyday .. The picture that you posted implies, a shotcrete with WWF mesh is applied ( on EPS ?) for earth retention and a thick plaster applied on the shotcrete .

I suspect the shotcrete got moisture and eventually the plaster spalled..

I wish, a second wall were constructed with insulation and a drain system ( enkadrain mat or similar ) and the interior plaster were applied on that wall..

The general rule for ordinary cement concrete, when the concrete gets dry , it will shrink.. when the dry concrete soaked in water, it will expand ..
But the shrinkage and expansion of concrete could not be the reason of spalling of plaster ..

Will you pls post some descriptive sketches for wall and slab ?