The program suggested by the piling contractor is to remove the upper 300mm (1 foot) of the concrete to eliminate any weak/dirty concrete however I think it will be more like 600-1,000mm (2-3 feet). We will see shortly I guess.
We are construction foundations consisting of 2,400mm diameter bored piles, 14,000mm deep. Bored pile terminates at ground surface. Subsurface materials are a thin layer of silty sand followed by mostly weathered tuff for the length of the pile so will use bentonite or Supermud for drilling...
Materials below 12m depth to about -35m are definitely highly plastic, marine grey silty clays, I have the samples in my office from the bored pile bucket. Upper material (0-5m depth) is a very fine sand which tends to flow given vibrations or a bit of water. Regarding the cement-bentonite mix...
Thanks for the insight on your experience. They use caliper logging in the petroleum industry wells I know but have never seen one used for a bored pile.
Still think the problem was caused by sloppy work by the contractor. I will put them & inspectors thru the '3rd degree' about the exact...
Been talking to the manager, good idea to talk to the driller too. Regarding the salt water environment, we usually flush the casing with fresh water, having cased off the obvious entry points for salty water and use bentonite mixed with fresh water. If hole is completed quickly the bentonite...
Thanks for all the quick and useful replies. By the way, the site is by the seaside and there is no evidence of artesian pressure but I wouldn't totally discount this either as the inspectors are not very experienced in this type of construction.
I agree with the reply of BigHarvey about use...
This is about a problem we are having for a 1.5m bored pile construction The following is the situation:
1. Boring data shows loose silty fine sand from surface to depth -5m, underlain by soft to medium stiff silty clay (N value=2 to 6) to -25m depth after which depth the clay becomes stiffer...