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Old 05-20-2011, 09:41 PM   #1
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Concrete Demolition


I have/had an old concrete slab behind my house that I wanted removed. Contractor came out with a bobcat equiped with a jackhammer and got everything but a 2'x3'x8' piece at the end. Guy tried for about an hour to split the large piece but it just kept slowly chipping, not breaking.

He said that he couldn't break it up with th bobcat and nothing larger can fit behind my house. I really need to get rid of this thing.

Any ideas? I have seen videos of chemical mixes that expand in drilled holes to break large rocks but then i would have to drill a bunch of 1" holes 3' deep, wait for the stuff to ship, then hope it works.

Anybody else ever come across something similar?

Thanks

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Old 05-20-2011, 10:02 PM   #2
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Concrete Demolition


Lived in Cheyenne for a time years ago. Long story having to do with missiles, the Air Force base and so forth. Wyoming's solution to any problem, whether rattlesnakes clinging to highways for warmth or site clearing for housing, is dynamite. It's cheap and it can be fast. Light it, through it off the back of the flatbead truck into a swirling mass of rattlers and problem resolved. Save for the potholes of course.

Not sure explosives are what you need to look into with this remaining slab situation. But there may be a firm offering such an approach near you for cheaper than other alternatives? Explosives, I hope, are not a DIY option though. I've only used such demo guys a time or two but found them surprisingly competent, coherent, and inexpensive compared to alternatives availed me.

I guess I am not clear as to why this piece alone remains? The jackhammer on the bobcat could not reach it or something about it was resisting attempts to break it apart? If it is just chipping I am worried your attempts to drill it with the usual will be equally frustrating. Do you think it alone was a section that got steel mesh, rebar or something?

What about the most fun tool on the planet rented for a weekend? A handheld one or two man jackhammer (with earplugs please).


Last edited by user1007; 05-20-2011 at 10:13 PM.
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Old 05-21-2011, 03:15 AM   #3
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Concrete Demolition


i lived in cheyenne for a while too. i never got to use dynamite on anything though. i would suggest the jack hammer and a quick saw. ive seen concrete demo guys on old bridge projects cut old bridge spans with some sort of cable with pletty of cooling water. im sure it would be exsensive.
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Old 05-21-2011, 05:14 AM   #4
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Concrete Demolition


I was on a job recently where they used the silent explosives. They drilled a series of holes, injected a compound, and waited for it to expand and crack the rocks. It was painstakingly slow and barely even did anything. Go with either the jackhammer, or the partner saw.
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Old 05-21-2011, 06:46 AM   #5
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Concrete Demolition


Why such a large, thick piece of concrete? Monolithic slab footer pour? Is it against the foundation or on the "far side"?

Dexpan and any number of "Expansive(ding) Demolition Agents" will do the trick. If the area is against the foundation. You have to give it plenty of room to push "out" or it will crack your foundation.
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Old 05-21-2011, 06:50 AM   #6
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Concrete Demolition


If you really want to have a blast Look into the Non-ex Boulder-Buster. $3000 bucks but then you can go into the biz for yourself.

Have a blast every day
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Old 05-21-2011, 08:16 AM   #7
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Concrete Demolition


Quote:
Originally Posted by CplDevilDog View Post
Why such a large, thick piece of concrete? Monolithic slab footer pour? Is it against the foundation or on the "far side"?

Dexpan and any number of "Expansive(ding) Demolition Agents" will do the trick. If the area is against the foundation. You have to give it plenty of room to push "out" or it will crack your foundation.
Funny you guys should say, I was was a combat engineer in the Marines and actually have plenty of explosive demolition experience. Only problem is its too close to my house and I like my windows.

The concrete remaining is on the "far side" about 12' from my house so expanding into the foundation isn't a concern. Have you used Dexpan before?

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Old 05-21-2011, 09:29 AM   #8
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Concrete Demolition


There have been a few occasions in my life where I had to remove thick concrete. One DIY method that is pretty effective is to drill a series of relatively closely spaced holes using a diamond bit equipped electric rotary hammer that you can rent at the local rental store. You drill say 1 inch holes every six inches, kinda slow but effective, then you can break the slab up using a normal concrete hammer, again the type you rent at the rental store. The key is that the holes make the hammer far more effective. For a thin slab, say six inches thick or less, you don't need the holes.
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Old 05-21-2011, 05:11 PM   #9
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Concrete Demolition


I went with the Dexpan option, will let you guys know how it turns out.
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Old 05-22-2011, 11:24 PM   #10
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Concrete Demolition


I cant believe he just gave up with the concrete breaker and left. I once spent 6-7 hours on one massively thick stair case with a breaker. It finally broke into two pieces that where manageable. I'm sure I should have gave up sooner, but I guess I'm determined...........
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Old 05-23-2011, 11:18 AM   #11
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Concrete Demolition


Update.

Well didn't see anything going on with the compound last night before I went to bed so I was a bit discouraged. Woke up this morning to let the dog out and heard a poping sound. Looked closer and there are hairline cracks that seem to go all the way through the block. Can't believe it!!

Excited to see what it looks llike when I get home from work.
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Old 05-23-2011, 01:49 PM   #12
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Concrete Demolition


Slo-mo demo.
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Old 05-23-2011, 02:48 PM   #13
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Wonder how it turned out?

I know when I'm in Sparks/Reno hanging out at my (ex) brother-in-laws the answer to everything is the AR-15, blow it up....or beer.
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Old 05-23-2011, 05:44 PM   #14
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Concrete Demolition


I went with Dexpan for a 6" or so deep and 4' x 2' very stubborn old step. 30 hits with sledgehammer chipped like 1 sq inch. I thought after having seen all the online photos, videos, and success that it was going to be the answer. I bought the smaller container (which I still only required 1/10th of) of #2, per appropriate weather, hammer-drilled many holes just over 1" diameter, much of the way through per instructions. Filled most holes, left some empty per instructions for expansion and place for others to crack to. I mixed product exactly to specs, with exact water ratio (to fill line). I waited, and waited, added water per instructions. I got nothing. Out of around 10 filled holes, ONE had a SLIGHT fracture. I keep wondering if I did something wrong, but followed instructions precisely.

Needless to say this was very disappointing. I will either wood-form around it in a limited fashion due to it's size/location, or spend the cash and time to rent a jackhammer and be done with it, feeling like I wasted the money on the Dexpan. Not a knock on the product per se' as I believe it has worked for many, but it did not for me, at all.
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Old 05-23-2011, 06:34 PM   #15
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Concrete Demolition


Wow that's a lot of work to end up empty. 6" doesn't seem very thick for something not to work. I think that if it's actually drilling easy enough, maybe you can drill a line of holes with your hammer drill then try to knock it off in chunks?

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