delay in the concreting of one of the piles 2

[chekre]

Good day,
During the excavation of the piles under a bridge, one of the piles has been excavated and the machine broke down. Therefore, concretre couldnt be placed inside the pile for more than 24 hours. The machine will be fixed this night and today will be ready.
the pile is filled with bentonite though its entire depth. I know that concreting should be placed without delay after the excavation but it was an accident.
Do u think it is ok ?

 

[jayrod12]

Ok so they drilled the pile the majority of the way, machine broke down so they backfilled with bentonite?

Then they are going to re-drill through the bentonite and the remaining depth and then cast the pile?

I don't necessarily see a large issue with that course of events but I'm no geotech.

 

[chekre]

Yes exactly except that they have almost reached the required depth.

 

[jayrod12]

Forgot to ask, end-bearing or friction?

 

[chekre]

I am not the designer. No enlarged bearing area at the bottom of the pile so probably friction pile.

 

[jayrod12]

perhaps then you should ask the designer, or the geotechnical engineer on the project.

 

[oldestguy]

It depends. How many piles in the group; soil type and load per pile among other things. This is one for a decision from higher up; not from this forum.

 

[aeoliantexan]

Specifications for this type of pier usually address this situation. The soil in the walls of the hole may have softened or a thick coating of bentonite cake may have formed on the walls, reducing the side shear resistance (skin friction). Sand and soft soil has probably settled on the bottom, reducing end bearing or increasing the settlement potential. Depending on the design, the engineer may require reaming the hole a few inches larger to remove the cake and softened soil and/or deepening the hole somewhat to get a clean, fresh bottom. The geotechnical engineer should be available to advise, or the structural engineer may know the local practice.