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Drilled pier foundation

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Rajendran,

For typical drilled piers (+/- 2 to 3 ft diam.) the rebar is normally
installed prior to placing concrete.  However, for auger cast piles the
standard procedure is to drill down to pile length, then pressure grout
through the stem as the stem is removed, and then the rebar is pushed into
the hole after the drill is removed.  We are using this procedure on a
current project with 16 and 24 inch piles.  The rebar cages are
approximately 30 feet long.  Note that auger cast piles are a real
speciality and require a very experienced contractor.  They also use a
special grout mix that is very fluid to allow the rebar to be pushed in yet
achieves 4000 psi or better at 28 days.

Thomas Hunt, S.E.
Duke/Flour Daniel

----- Forwarded by Tom Hunt/DFD on 03/06/01 02:01 PM -----
                                                                                                                   
                    Padmanabhan                                                                                    
                    Rajendran            To:     seaint(--nospam--at)seaint.org                                                 
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                    oo.com>              Subject:     Drilled pier foundation                                      
                                                                                                                   
                    03/06/01                                                                                       
                    12:41 PM                                                                                       
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Drilled pier foundations have reinforcement (vertical
bars + ties or spirals) in the upper few feet of the
piers. Recently, I heard that it is common for the
construction folks to place the pier concrete and then
push a preassembled cage of reinforcement through the
concrete. Does this method guarantee that the rebar
can be placed reasonably close to the way it is
detailed on the drawing? Is'nt there a good chance
that the rebar may be bent and mangled?

Rajendran