Cracks in foundation
Cracks in foundation
(OP)
Hello,
We have a 70 cm raft foundation, it was poured around 1 month ago, last week we have noticed cracks connected to its corners.
The image shows these cracks (red lines).
Are these cracks due to the shape of foundation, (knowing that no corner reinforcement were provided) , or it could be because of soil settlement.
Thank you
We have a 70 cm raft foundation, it was poured around 1 month ago, last week we have noticed cracks connected to its corners.
The image shows these cracks (red lines).
Are these cracks due to the shape of foundation, (knowing that no corner reinforcement were provided) , or it could be because of soil settlement.
Thank you






RE: Cracks in foundation
RE: Cracks in foundation
The foundation is around 40 x 40 m and the crack continued along the whole foundation length, which made use worried about the possibility of soil-structure interaction since we have a limestone soil with small cavities.
RE: Cracks in foundation
The micro-management of the soil-structure interaction problem that also cannot be altered.
Expect some addition changes/cracks in the crack patterns as the concrete continues and experiences some thermal changes if you are in a cool climate.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Cracks in foundation
RE: Cracks in foundation
Dik
RE: Cracks in foundation
Never sawcut a structural mat (raft) foundation. Sawcuts and tooled joints are primarily for thin lightly reinforced slabs on grade.
These cracks are somewhat preventable [manageable and kept very small] by:
a) more X-Y reinforcing,
b) corner reinforcing, and
c) construction joints ("cold joints")
RE: Cracks in foundation
Since the shape has likely caused the cracking, I'd have poured it in separate 'chunks' and may have increased the reinforcing, too. Don't know how it's loaded.
Also, low slump and superplasticiser and larger aggregate size.
Dik
RE: Cracks in foundation
Assuming you have top and bottom reinforcement (of course you do for a 70 cm raft over karst topo), carry on. If these cracks were due to settlement, (in the unlikely event that you have a sinkhole at each corner of your new foundation) You should be able to verify by checking elevations. In which case, you should provide Mr. Magoo, your geotech, as an offering to this newest cenote.
RE: Cracks in foundation
Could you please check the images for the cracks, we are about to cast another foundation next month and we need to try to avoid these cracks.
RE: Cracks in foundation
Dik
RE: Cracks in foundation
If you must, you can add a top mat of welded wire reinforcement to redistribute the cracking over more area (more smaller cracks that no one will ever see again). Throw some small corner bars at the reentrant corners as well.