Crack on basement slab 1

[Simlac450]

Hey guys,

I have a situation there, a costumer called me for an evaluation of structure and the building is in bad shape, a lot of abnormal stuff i.e. steel beams not laterally supported on more than 34 ft, crushed joists, but the weirdest thing is the slab on the ground (non structural) there are a lot of huge cracks in it, and there is a lift up in some part, in the inside the foundation wall are insulated by polyurethane but on the exterior there is no visible crack and the building has a brick veneer all around and there is no crack at all in the mortar joints, so my question is what do you think could have broken that slab ? The house is 400 ft from the St-Lawrence river, Quebec and the building has 2 pumps in the basement.

 

[Simlac450]

picture of the up lift

 

[kipfoot]

sounds like slag or some other expansive material under the slab.

 

[dik]

Some questions...

What are the foundations? and what is the soil? and what has the weather been like lately? Wet/dry and plastic/non-plastic soils?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Simlac450]

The foundation is made of concrete, for the soil I don't know, so far no soil test has been done. For the weather nothing unusual, not dry not wet, but if the whole building was on an unstable soil the brick veneer and the rest of the foundation would have some cracks, no ?

 

[dik]

Very likely... That there is no distress to the exterior is very good, and indicates that the issue is constrained to the slab. Carefully lok at all components to see if there are signs of distress.

Does the slab need repairing? Can it be done with 'mudjacking'? The 'lip' is not quite a tripping hazard; can it be ground down if necessary.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[HTURKAK]

With the info. provided, it is hard to predict the reason . However, we are free to speculate ..My opinion is, the basement slab is casted on non-compacted fill..
Will you post some as - built details showing the foundation system, slab , structural system ?








Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[JedClampett]

If the walls are on a deeper foundation or piles and the slab is on some gumbo, I would expect this.
Also, if the pumps are vertical turbine pumps, the excavation for the cans can be quite deep. A normal contractor will do the normally inadequate job compacting the soil around the pump cans and you'll get settlement. And settlement adjacent to the pump cans will look like they're lifting.