How would you remove a concrete pier?

[CurlyDave]

You can get a small scaffold at HF for ~$150.

If the weight of the column is a real worry start jackhammering at the top and work down.

 

[Daves Maple Farm]

Let my wife on the tractor!

 

[Gary Fowler]

I have never seen a column without rebar. You can find out easy enough with a little bit of chipping. The rebar will be within 3" of the outside of the pier. If it has standard construction, it wil have a least 4 vertical rebars (maybe more) then about every 12" a circular ring will be holding the verts together. You can chip all the concrete away and the column wont fall. I would get a 50# jackhamer and start ringing around it chipping out as big of a chunk as it would break while resting your chisel point on the slab and angle in at a 45 degree. You should see rebar pretty quickly. Assuming it has rebar, chip away all the concrete about a foot wide, then fell it just like a tree by cutting out the rebar on one side on the side that you want it to fall and work around to the back side. It should start to fall over a bit on the second cut if it has only 4 verts. Be extremely careful with the last cut as it will fall quickly when the load exceeds the rebar strength. I would use an OxyAcetylene torch if possible as you can see the steel start to stretch a bit before it fails. With a cut off saw or grinder you wont have any warning and be prepared for it to bounce backward a bit also.
That pier could be anywhere from a few feet below grade setting on a massive concrete slab to more than 60 feet in the ground if it is a friction pile so I would just chip it down 3 or more inches below the top of concrete pad and pour a slab back on top. Leave the rebar in it and bend them over to form and L shape. This will help anchr the concete patch

 

[vtsnowedin]

Concrete is roughly 150#/CF. I figured your 18"ﾘ x 72" pier is less than 1,300#. We handle concrete cylinders on a regular basis. We have an order now for some that are 24" in diameter and up to 10' tall. We lift them using three different methods:

.

Check your math.
I get it from
pi *r^2*L* UWT. As the radius is 9 inches or 0.75 ft you get 3.14159 * .75 * .75 * 6 * 150= 1590lbs.

 

[chim]

Check your math.
I get it from
pi *r^2*L* UWT. As the radius is 9 inches or 0.75 ft you get 3.14159 * .75 * .75 * 6 * 150= 1590lbs.

You've caght my brainphart (3 quarters vs 2 thirds)- I plugged in .667 in lieu of ..75. DUH!

 

[sparc]

Check your math.
I get it from
pi *r^2*L* UWT. As the radius is 9 inches or 0.75 ft you get 3.14159 * .75 * .75 * 6 * 150= 1590lbs.

What does it matter? The 150 is a ballpark number for estimating. I would take that 1590# and call it 2000 (minimum) for the puspose of sizing rigging, etc.The weight of the actual concrete in his pier will vary from 150lb/cf depending on the aggregate and other components used in the mix, plus the weight of the rebar and/or wire.

I like the engine hoist idea, taking a couple bites you can have it flush with the slab in one or twmanageablele pieces.
Seems like the easiest and least expensive way to go. If you don't have a engine hoist you can rent them by the day, or maybe can borrow from a friend. Worst case buy one at HF and sell it when done for a few bucks less than you bought it for.

 

[vtsnowedin]

You've caght my brainphart (3 quarters vs 2 thirds)- I plugged in .667 in lieu of ..75. DUH!

I expected you just hit a wrong key seeing as how most of my computations have one or two on the first try.

 

[vtsnowedin]

What does it matter? The 150 is a ballpark number for estimating. I would take that 1590# and call it 2000 (minimum) for the puspose of sizing rigging, etc.The weight of the actual concrete in his pier will vary from 150lb/cf depending on the aggregate and other components used in the mix, plus the weight of the rebar and/or wire.

I like the engine hoist idea, taking a couple bites you can have it flush with the slab in one or twmanageablele pieces.
Seems like the easiest and least expensive way to go. If you don't have a engine hoist you can rent them by the day, or maybe can borrow from a friend. Worst case buy one at HF and sell it when done for a few bucks less than you bought it for.

What does it matter? Well to a guy that has a tractor that can lift 1500 pounds max a whole lot. All you have to do is look at a few crane failure videos and realise that in every case someboby miscalculated something before the lift. 150 is a pretty good figure for concrete. very few mixes weigh much more then that even including the rebar and not many weight much less then 140 except special light weight mixes for high rise buildings that use light aggregates like pumice.
A good safety factor is good as in being able to lift twice or three times the load but in day to day work with distances and positions often less then ideal most lifting machines get worked at very close to their maximum ability on a regular basis. The question is what do I do if I go to pick this load and can't hold it? Can I drop the load and save myself and the machine or am I committed and failure is not a reasonable option. Best to have that and all the math though through before you pull the up lever.

 

[chim]

It does matter. Mistakes like that can lead to breaking things and hurting people.

While I checked the math twice before posting, I used .667 as a multilplier insted of .75 each time. When I saw vtsnowedin's post I clicked the values into the calculator in inches (3.14 x 9 x 9 x 72 / 144 / 12 x 150 = 1589.625#. It was then that I realized what I'd done.

BTW, we were playing with three 24"Ø x 9' cylinders yesterday trying out some new cribbing ideas for shipping. Having 5T overhead cranes at work kinda spoils you when it comes to moving stuff around indoors.

 

[vtsnowedin]

OK having the math issues sorted out we are waiting on the results post on how this pier got removed. Hope the project goes well.