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90 ft. Auger Cast Piling
2

90 ft. Auger Cast Piling

90 ft. Auger Cast Piling

(OP)
We have a project in south Louisiana proposing to use 18-inch diam x 90 ft. auger cast piles. I assume the cage will have to be placed after the auger is removed with poor soil conditions we have here. Does this sound possible?

RE: 90 ft. Auger Cast Piling

That's probably your best option.

The other option is to use casing, which requires more labor and more machinery.

RE: 90 ft. Auger Cast Piling

(OP)
So the cage will have to be pushed into place with hopes its straigh and true before the concrete gets to stiff? I see some problems.

RE: 90 ft. Auger Cast Piling

I asked the same question, but with 60 ft. long piers.
thread256-239787: Large Auger Cast Piles
Not much help there, but there was a great Federal Highway document that I found on Auger Cast.  I'll look for the link.
 

RE: 90 ft. Auger Cast Piling

Augercast piles do not use casings, they have the 'hole' held open by the grout that is pumped in.  Since the grout uses sand as it's only aggregate, it allows for the cages to be placed.  

If your piles are 90 feet deep, then the minimum cage length should be at least 30 feet (1/3 total length) depending on the seismic site class.  Proper use of centralizing devices and an appropriately design grout mix will allow for reinforcing cage ease of placement.

As a side note, some projects in Florida require full length cages, and their piles can exceed 100 feet.  The high water table prevents the grout from curing very quickly.

RE: 90 ft. Auger Cast Piling

(OP)
Think that's got it guys. Thanks.

RE: 90 ft. Auger Cast Piling

dirtydude,

that post all made sense up to "the high water table prevents the grout from curing very quickly". I doubt that's the case.

RE: 90 ft. Auger Cast Piling

Zambo..you're right.

RE: 90 ft. Auger Cast Piling

Might not prevent it from curing normally, but might prevent it from curing at all if sections of the pile are infiltrated.  I feel uncomfortable with depending on grouting below the water table, particularly that far down.

RE: 90 ft. Auger Cast Piling

(OP)
hokie, Well now I'm back to uncomfortable. We definately have a high ground water table. Drainage ditches all have standing water year round.

Install a couple of  auger cast piles and load test them. Do they need to cure 28 days?

There will be 60 ft. timber piles within 7 ft. of the auger cast piles. Should these be installed first? Will the driving vibration disturb curing of the grout?

RE: 90 ft. Auger Cast Piling

REIIC...no real need for concern.  A key to successful Augercast installation is monitoring the critical aspects of the application.  The auger extraction rate and grout pressures are critical.

Reinforcing cages can be pushed into the top of the pile and centered.  If subjected to uplift, a single bar in addition to the cage can be extended deeper into the pile.

Your application is not uncommon.  Vet the contractors for experience and check successful applications.  Provide full time monitoring of the application, preferably by an engineer.  

RE: 90 ft. Auger Cast Piling

If the soil for which the pile is installed is 'dry', it will wick away whatever moisture is within the grout causing it to become less plastic.  That is the statement I was trying to make.

Pile load tests on augercast piles can be tested within 7 days if the grout mix is adjust appropriately.  Keep in mind the point of a pile load test is the verify geotechnical assumptions made during the design.  The structural integrity of the pile should not need to be tested if the pile is installed properly.

RE: 90 ft. Auger Cast Piling

dirtydude,

it is correct that rather than the high water table causing the curing issue there is a consoderation that if you are casting against dry soil you can lose moisture from the grout.

If possible I would wait 28 days for the pile test. There is some drying shrinkage as cementitious materials hydrate and leaving a longer period before testing will ensure that any space has been closed.

As Ron states the work procedures are key to ensuring that the grout pressure keeps the water out of your excavation and avoids infiltration of water into the pile. Grout quality and density are also importance.

RE: 90 ft. Auger Cast Piling

Just to point out that there is not much of a cage, only the diameter that can fit through the center of the augers.  As noted above, often this consists of a single bar at greater depth.  I would generally not trust these things for any significant lateral pile capacity (since I am in a high seismic area.

RE: 90 ft. Auger Cast Piling

Geostructsparks,

In all of the ACP piles that I have done, the cage is installed after the auger is removed from the hole.  In that way the cage can be of any resonable size.  The length of cage shold be no longer than is needed based on a lateral analysis of the pile and uplift capacity (if needed) should be provided by a single bar to the bottom of the pile.

RE: 90 ft. Auger Cast Piling

Zambo - While waiting 28 days may be the prudent thing to do, think of the cost implications of having the construction equipment, and possibly the crew, on standby.  These costs would outweigh any benefit of the additional cure on the pile, in my mind.

RE: 90 ft. Auger Cast Piling

(OP)
Any concerns over driving timber pile ajacent to ACP or should all timber piles go in first. Cure time will take care of itself if timber piles are installed after ACPs. There are 300 +/- timber piles.

RE: 90 ft. Auger Cast Piling

I'd put in the timber piles first.  The auger cast installation should only disturb a very local area, while the pile driving can vibrate the whole site.

RE: 90 ft. Auger Cast Piling

Putting the timber piles in first is one solution, although it makes the site somewhat difficult to navigate for the augercast pile installation.

The other solution would be to drive the timber piles second, and ensure that the initial set has taken for all of the augercast piles.

Either way, vibrations are a concern for the augercast piles.

RE: 90 ft. Auger Cast Piling

Studies have shown that when the spacing between a cast concrete pile and adjacent driving or drilling exceeds about 3 pile diameters, the effect of drilling or other vibrations is insignificant to the concrete.  

Look for study done by Florida DOT at Florida Atlantic University in late 1990's.

RE: 90 ft. Auger Cast Piling

In my experience, and echoed by others, there can be water loss from the grout into saturated sand as well as dry soils that can make installation of a cage after grouting difficult.  One solution is to redrill and regrout the pile after a short time; often it will then accept the cage.  You haven't told us what the soil conditions are, but I assume you may have weak clays over sands.  You may be able to get a cage in if it does not go below the bottom of the clay.

A single bar or bundled bars can be installed through the hollow stem of the auger in most any soil.  Cages are nearly always installed after grouting.

If seismic forces, tension loads, swelling soils, and lateral loads are absent, a light cage about 15 feet long to handle incidental moments may be sufficient.  I have seen this done on thousands of piles in the midwest.  Check your local building code, of course.

Local ACIP contractors can probably tell you what is feasible after they see the boring logs.

I would be concerned about the water table only if it is above the pile tops, which can lead to bleeding and cement loss.  The ability to be installed in wet soils that would cave in open holes is the main appeal of these piles.

RE: the timber piles.  Excessive soil removal during installation of the ACIP piles could undermine the prevously installed timber piles.  Lateral displacement during driving of the timber piles might damage the previously-installed ACIP piles.  Be careful!

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