ATM Concrete Piers

[Adam Perkins <scopeguru@yahoo.com>]

> At 10:57 PM -0700 6/24/99, Tom & Lou Krajci wrote:

> I've seen lots advice on
> >pier materials, dimensions, etc., but I don't
> recall any basic advice for
> >someone who's never poured concrete before.
> 
> >What simple tips will ensure success for a
> beginner?


Hi,

There are a few good reasons to use something like sonotube for a
concrete pier.  Being round in cross-section, it cannot bulge under the
enormous weight of wet concrete.  

I don't know what the frost depth is in your area, but "frost heave"
may be a concern.  By using formwork IN THE HOLE rather than just
forming above the ground, you ensure that the moving ground cannot get
purchase on your pier. By placing the tube 24" or so down into the
hole, you can avoid alot of headaches later.

Use lots of steel (rebar) in your pier, concrete has lousy tensile
strength.

For a "tall" pour like a pier, watch out for air pockets as you pour,
they are ugly and can weaken your pier.  Poking around with a long
length of rebar as you pour will help break any bubbles, you'll have to
do this every 6-12" as you pour.

Try to get as uniform a consistency as possible as you can while mixing
conc.  If you're mixing by hand, you may find yourself mixing MANY
wheelbarrows worth.  It may be worth the trouble of renting a conc.
mixer/hopper.  Some places actually can provide these full of pre-mixed
concrete, you just tow the thing to your site and pour (do NOT stop for
lunch on the way).

The setting pour does have to stay damp.  Try to keep the sun off it. 
You can put damp rags or newspapers (which may stain...) on the
surface.

The best way to anchor things in concrete is to set them before thigs
set.  A few J-Bolts in the top of the  pier will hold an enormous
amount of weight.  Keep them at least 2" from the outside edge, and 6"
deep or longer.  Its worth making a wooden jig to hold the bolts plumb
and correctly placed, you cannot fix this later...

I deal with concrete pretty regularly, and actually was involved with
the pouring of a large concrete telescope pier.  Feel free to send me
whatever specifics you have, and I'll give what help I can.

Adam Perkins
Covington, Louisiana
(504) 893-5938


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