Concrete Demolision and Removal

Sounds perfectly miserable

1. Hard hat

2. Hearing protection

3. Face shield

4. a selection of short and long air powered jack hammers, electric would be quieter

5. Concrete saws - don't make these in quiet versions.

going to be a lot of hand work if I understand.

Or explosives! Proper application of explosives....wait - I stole that

Emmett

Excellent points!

Still sounds miserable - resembles too much the work that drove me to software.

You did not clarify the estimated thickness of the concrete you are planning to cut through. If it is thicker than four inches, your best bet is to either use a tool called a Darda Rock Splitter or Bristar. The rock splitter requires a series of sized holes drilled into the concrete and then the split shaft of the tool is inserted just to the bottom of the hole. A long, low angle wedge is advanced through the split shaft by means of a hydraulic ram that is powered by an electric/hydraulic pump and this wedge forces the split shaft open which creates a crack through the concrete. Rotating the tool 90 degress provides cracks in two axes. If you perform this operation over a grid layout, the subsequent jackhammering will be much more productive.

Bristar is a fairly expensive chemical that expands with the introduction of water. Its use requires a series of drilled holes as well and it is then poured into the holes and water is added. The extreme pressure that it produces fractures the surrounding matrix.

Either of these methods will introduce enough fractures into the removal area that the subsequent use of a jackhammer will be far more productive than without the use of these tools.

If you are at that depth, you definitely need a source of forced ventilation, as carbon dioxide and carbon monoxide are heavier than air and can accumulate in a hole to deathly levels. You could rig a well wheel and a 5-gal bucket to remove the waste material. You should consult with OSHA for guidance regarding work in a confined space as the last thing you need is to have fatalities on account of not being prepared and not knowing the potential risks involved.

Two simple easy solutions for you

1. Hydraulic diamond wall saw - though if the cut is only 4 ft hand held would be best. You get them via concrtete cutting companies who will do the work for you. they cut through reo easily enough

2. hydraulic or electtric diamond drill though the hole will be round of course! though they could stitch drill squarish ones

Again hire a concrete cutting company . If you are in Aus DIACORE in Sydney are your people.

Hello civil6711:

Lets get this clear. You are going down 50 ft to remove a concrete block 4x4x4ft?

Why? Is it a bomb shelter? No chance of any pictures? Or possibly telling us where it is or what it is and we can look for pictures?

Sounds interesting to think about, but, now to actually remove.

take care.............

Hello civil6711:

I did not notice it was your first post.......Welcome! You will find someone here that will have the know how to help for sure.............famous last words?

Try a product called Dexpan.Google search them.It is a grout that when set exerts 18000 psi causing fracture.

The hole is in the bottom of a pier of a dam. The concrete is about 4 feet thick. We have all ventilation taken care of and our Safety/OSHA guy will be on sight at all times. I am mainly wondering if our guys can do it in house with the right tools or if we will need to contract out.

All the posts have been very informative. This is a good sight. Can't believe I haven't been here before.

A few of the guys have mentioned the sort of chemical slugs that are inserted in drilled holes, allowed to expand, thus fracturing the concrete. That stuff does work, but you do need to read the instructions. It takes longer for it to work when the concrete is cold. The other suggestions of electric jackhammers and concrete cutting saws are of course correct. A further note is avoid running the jackhammer for much over an hour per man, as it will tear your back and all up.

PS, start demo at edges of concrete instead of in the center.

Good luck did something similar a while back and it was mainly chipping away with electric jack hammer' with a grid pattern of saw cut's we also had a man with a shop vac of sorts to catch the dust from the saw, this helped considerable since the ventalation ducts we had were not enough to handle all the dust. we also modified a 30ft conveyor we attached metal buckets to lift up the debris. If i remember correctly we had 5men on this and one confined hole watch person. your asbuilts of what is there will let you know if a conveyor can be used. good luck its definitely a hard task however you go about it!

You might take a look at the product touted at this site: <http://www.lencocanada.com/pdf.d/200-09.pdf> Burning bars can eat through concrete and steel re-bar. You would, of course, require proper ventilation, but you already said that you had that aspect covered. Obviously, if there is any combustible gas present, these would not be apropos but from your problem description, this is probably not a factor. You would have to drop an O2 supply line from above to provide the oxygen feed to operate these. I used them years ago to cut through a stone and concrete wall that I was demolishing, obtained from a former boss of mine who began selling these.

#1 Safety in confined spaces and protection of the workers therein is the first and formost concern. I have used bristar and another similar product to good use. The trick with this large a chunk is to do the operation sequentially. Drill the holes at one time, but install the expansive grout in successive rows, from the outside in. This gives you the most bang for your buck.

Not going to be a fast operation. Remember there is always time to do it right the first time..

I read it incorrectly, but the process is the same. The expansive cements work best when there is a place for the concrete to expand and to crack. These materials still require jack hammers/ For this size a 30# rivet buster with a point works well. It can be easily directed and not so heavy that it beats the operator to pieces.

Check out this link http://www.capprex.com/ It covers controlled foam injection for removing hard rock,used in mining, etc.No explosives required. HTRN

Interesting info! thanks!

Ouch, Shoring, H2S and O2 Monitors, forced air ventilation, above ground personel to monitor safety full time, and a tethered recovery system. Also it will be noisy down there with a concrete saw, so serious hearing protection. Hmm, going to need cerified trained personnel for a confined space entry and a permit also. I would say not cheap.

50 ft below ground and near water? When you finally break through to the ground, what will you find on the other side? Will it be water under pressure? Maybe a think about this aspect is worthwhile.

Hello civil6711:

Good answer from snowplow! This is what it does! Sounds just the right stuff for the situation?

These are distributors: hankinsstone.com

http://images.google.com/images?hl=en&q=Dexpan&btnG=Search+Images&gbv=2

This is the google pictures of this stuff and other sellers.

Looks formidable stuff to just maybe drill a few holes and come back in a few days to see the 'damage?

Good luck and take care............