Concrete Demolition.

I'm not too sure about which acid would be best to use on concrete, but I remember years ago the news was full of stories about acid raid and its effects on concerete. If I remember correctly, the main acid mentioned in those stories was sulpheric acid. I believe the effect was more erosive than corrosive, and, unless the solution is very strong, it will work very slowly. If the solution is strong, it might produce hazardous fumes and you will have to be very careful handling it. I would avoid using chemicals for just this reason.

One of the first jobs I had was removing the mortar from brick from demolished buildings so the brick cold be reused. Sometimes we would wind up with a large chunk of brick stuck together that would be about the same size as, if not larger than, the slab you are talking about, except that the chunk would not be as thick. We would break up a chunk like this by "sacrificing" one of the bricks in the middle. Someone would take a sledgehammer or a large axe and beat on the sacrificial brick repeatedly, until the brick was reduced to rubble. The shock waves from the beating would break up the large chunk into smaller ones that were easier to handle.
You could use this method on your slab. Mark a spot near the center and hit it over and over with a sledgehammer until that spot is reduced to powder. The rebar will give you some problems that we didn't have to deal with, so you might need to have a good hacksaw handy.

Or you could check to see if there are any tool or contractor equipment rental firms in you area that have circular saws capable of cutting concrete and steel.

I assume this slab is in the ground. If it is, you might want to dig around it by hand before trying to break it up, especially if you are going to use a saw to cut it up into smaller pieces.

Without using heavy equipment, I believe you will have to do some manual labor, or hire someone to do the work for you.

Just yesterday I saw rock that was treated with an acid. It was as soft as a rusk dipped in coffee. (well almost)

It should work with concrete as well.

what was the acide

You don't want to use heavy eqiupment,you definately DON'Twant to use chemicals (that will leave you a mess to clean up like none you have seen before) Getting a permit to use chemicals in that quantity might be impossible. The only other avenue you have is to start at one corner (so pieces have some place to move to) with a jack hammer and brake the concrete. Brake the concrete from arround the rebar and remove by hand. Is there a reason why you can't have this slab removed with a backhoe? A good operator could most likely reach over it, hook under it and lift it out to a waiting truck in just a couple minutes. Even if he had to bust the slab in two because it was too heavy to move all at once, it still wouldn't take all that long.

"break or demolish a concrete slab of one meter by 3 meters and 1 meter thick? Rebars of about 16 mm spaced 20 cm apart."

A steel pipe fed with oxygen can be used as a lance to cut concrete block, and rebar all at one and the same time into smaller sizes for disposal. I forget the name of the process and details as it has been 40 or 50 years ago that I saw it demonstrated. Need fire protective gear for the operator, and a good supply of pipe and oxygen.

Many years ago as a student I worked for a heavy moving company. (Ok, so it was 40 years ago.)

I will assume the concrete is free standing, if not, saw it clear, there are many companies that do that. They can saw it into smaller chunks, rebar and all, in relatively tight quarters, typically 1 meter clearance on all sides is required, though some companies require less.

Once the concrete is free standing, or jack it up so it is, then use pin rollers (2" steel shaft) and roll it out of the way, or put it on a dolly.

If this is a DIY backyard project and you don't want to spend any money, get yourself a big sledge hammer and start hammering. It should take only about a month of work.

For a few more dollars rent an air jack hammer, and it should only take a couple days.

You will need a few strong arms to carry the pieces out, and then find somewhere to dispose of it.

Another technique that used to be used "on the farm" for big rocks was to build a big fire and let it burn for several days or as required to get the rock really hot, then use LOTS of cold water to rapidly chill it. It would fragment into smaller pieces.

1m thk. Concrete.

Noisy way--Pneumatic percussion chisel with 3 men.

May be possible to complete in 8Hours.

It is interesting that you call this cast concrete with dimensions of 1 meter by 3 meters by 1 meter a slab. That is the last thing I would have called this massive chunk of concrete. And it is reinforced with 16 mm bar that is only 20 mm apart. I would call it a massive amount of reinforcement surrounded by some concrete.

Your not eroding, smashing, cutting, demolishing, etc. this piece of concrete / reinforcement very readily no matter what you do. If it wasn't reinforced, you would stand a reasonable chance with a jack hammer or expanisive injections. But, because of the reinforcement you described, it will be able to resist tension and shear forces as readily as compressive forces.

Good luck. I would not want this battle.

Thats why I suggested just move it.

If you do not want to use heavy equipment to break or remove that piece of reinforced concrete slab, then you can use an electric jack hammer. This power tool is simple to use. No need for noisy air-compressor to power it up. Just plug it into a suitable electrical outlet and you're ready to go. You select the size of the jack hammer and the type/size of bit you are comfortable with, that you can maneuver easily around the rebars when breaking. It will be wise to work around a rebar at a time until you can free it up to be removed from the concrete, then work on the next, then next.... It will take you sometime to break the concrete into small pieces and remove the rebars one by one without even using a hacksaw (just use cutter/plier to remove the tie wires).

It's your choice now whether you dispose off or recycle the materials.

Having read other's comments which I see as reasonable and I cannot add any further suggestions for removal.

Stop the exercise and ask:- "Why remove it?"

You do not say where it is, but use imagination

It could become a very permanent table

It could be used as an anchor for tying up a dinasoar

Or make a small hole in the top and declare it to be the world's largest ashtray - The tourist attracting possibilities are enormous - open a cafe and discus arrangements with tour companies.

It can be worth a lot more than rubble.

Good Luck

Try this site. Silent expanding explosive

Used it to crack large Bundies (Rocks) where it was close to buildings and personnel.

Most excellent stuff. Just drill a couple of holes and fill them with this.

The steel might give you some problems but it should be enough to do the job you desire.

That looks just the stuff this guy needs...

Fascinating, thanks for the link geomech, I didn't know such stuff existed...

John.

This is an excellent starting method, do the rest with jack hammers.....

What have you got against explosives anyway, the control these people have on its effects is unbelievable today.....

Another possibility.

Chip or jack hammer away enough concrete to expose some rebar, load the cavities with thermit and let the intense heat crack the conncrete and melt the rebar.

Lovely stuff Thermite!!

Andy: It will at least create a Lovely Thermite fireworks display!

As it always does!!

You pray that it will NOT do the job fully first time, so that you can do it again!!!!!

Hello,

Very simple. Wear protection clothes and a helmet. Take a large about 1.8m high and diam 200mm oxygen standard reservoir filled with oxygen up to about 200bar. Next - fix a pressure reducer to reduce the pressure from 0 to 0.5 bar. Fix a flexible pipe with a deflagration stopper in line, so that no flame can return to the reservoir. At the end of the pipe fix a six meter long iron pipe 1 inch diam with full of iron threats diam 10mm in it.

Make a cole fire and open the oxygen valve. The fire will light up with the oxygen. When the end of the pipe is red, open the oxygen even more, and you will see the iron pipe burning. Put the burning end of the pipe against the concrete. It will form a liquid Calcium-iron -carbonate and you are able to cut the bloc into pieces.

Best regards,

Theo

The technical term I believe is "Thermic lance", well liked by safe breakers as safes are often made of steel and concrete too!

Cuts through just about anything, but has a very high usage of pipes and oxygen!!

"You pays your money and you makes your choice!"....old English proverb.

If you really want to use chemicals, then use hydrochloric acid (also muriatic acid). It dissolves concrete.

Hi!: you might consider the ThinJack - an hydraulically inflatable steel envelope. Often used in oil and gas industry for splitting/separating stuck flanges but also for removing concrete weight coatings off pipelines. see website with rock splitting images www.mamut.com/thinjack Thin Jacks can be sized for most requirements;a quiet and environmentally sound option. regards Alastair MacDonald arm@thinjack.info

Along the same idea, I remember (another summer job decades ago) an access hole had to be punched through an existing concrete wall about 2 ft thick. A pattern of holes were drilled and then an Hydraulic "expansion bolt" type device was inserted it expanded and fractured the concrete into the surrounding holes. I believe the holes were drilled with a round diamond core saw and were 1 to 2 inches in diameter, exact dimension I have forgotten.

The nonexplosive expanding compound looks like more fun though.

There are companies that will come and saw your block in to as many pieces as required to move it. They have a machine much like a very large chain saw.

There are other companies and maybe the same one that can cut the slab with a high pressure water cutter.

In Belgium there is much granite mined and since the government made it illegal to use explosives they use these water lances.

Jack it up. Put slings under it and crane it away to a vehicle, from which it can be dropped into a concrete crusher.

That's around 7 metric tons of weight...!

As a student I worked in a natural stone division sawing marble into sills and countertops etc.

We routinely lifted 10+ (long) ton blocks with slings so we would not damage the rock.

I think the problem on an industrial / commercial level is no big deal.

For the DIY backyard group it is a big (and heavy) problem.

No matter what, money will be spent, and effort expended.

Matter of fact most contractors that handle concrete placement, sawing, and demolition can handle the problem many ways and quickly.

The DIY group will not have even the jacks to lift it, let alone diamond core drills or saws.

If I were responsible for the removal I would be looking up the local contractors and getting competitive quotes.

The simplest way to get rid of it if feasible is to dig a hole beside it and let it fall in.

Go at it with a really good sized oxy-acetylene torch. It'll crack and pop so you want protective shielding, but it will chew it to bits.

Lithium Bromide solution as used in absorption chillers does bad things to concrete. It is readily available. It is extremely hygroscopic and pulls the water molecules out of the concrete matrix reducing it to powder. I don't know how fast it works though.

We had some lithium bromide to dispose of and the local sewer district said that as long as it was sufficiently diluted it could be flushed down the sewer. In a concentrated state though, you don't want to get in on your skin.

Hi to all!

Many thanks for the information posted for this query. A friend actually asked me this question. For all we know, it could be a treasure vault that contains a lot of surprise. It may not be all solid concrete at all. Again, thanks...

Hmmmm,

Are we all party to the heist of the century?

I've seen a crew of "undocumented workers from Mexico" take down a two story house and the entire concrete slab, including the driveway with paper clips they found on the way to the job site and a water hose, in two hours.

dexpan