Cutting reinforced concrete - how to get after it

[Boissal]

I searched the web for some time and came up with enough opinions to write a couple books. I searched on here and didn't find much.
How would you go about removing a section of reinforced concrete wall? At some point in the distant past someone converted the back porch of my house into a room, enclosing the whole thing. He left behind a mess of concrete and foundation and what I assume was a support for the stairs to get on the porch. I want to cover all that ugly shit and have to knock down that wall which is still attached to the house.
Pics attached for clarity.







Options reviewed include:
. Sledge hammer and a lot of motivation - not my top choice at the moment due to wrist issues from climbing and the fact that separating the wall from the house may not be all that clean...
. Variation of the above including using the hammer drill in strategic spots to weaken the structure and eventually attack the rebar with an angle grinder - again, I'd like to reduce the amount of brute force involved so I can finish the climbing season
. Get my hands on a concrete saw and try to do a clean job - least unreasonable option at this point although cutting the base of the wall isn't going to be fun and I need to shave off as much as possible to get the area somewhat level.
. Use non explosive (!!) "expansion paste" in drilled holes - not even sure where I can get my hands on the stuff, would rather avoid expanding into the house's wall....

Thoughts? Opinions? Recommendations?

[timmaio]

Water cooled concrete saw for the majority of it. After that sledge hammer. Angle grinder with diamond blade to finish cleanup work.

It shouldn't be hard to rent the concrete saw. Maybe 100-200 for a days rental including blade wear. Electric is much nicer than gas if they have it. (Less weight, fumes)

[::: :::]

rent concrete saw at home depot or other equipment rental place
cut a vertical line to completely separate the stem wall from the building foundation (you don't want to be hammering/vibrating the existing foundation to remain, if you can help it)
you may need to dig to have enough acccess to the stem wall's foundation too
then bust up the remaining bits with a sledge or jackhammer

[DJSapp]

From a guy who contracts this kind of work for a living (on a much larger scale)

1. Rent the biggest jackhammer you are comfortable lifting. And when I say lift, I mean lift for 6-8 hours at a go. A chipping gun with a bushing head for the detail work near the house
2. Buy a diamond blade for a skill saw ($15-20). If in your budget, strength capacity and confidence rent a chop saw with a larger diamond blade for better results
3. Get a properly fitted respirator, face shield and shave so the respirator actually works (seriously, I've seen too much bad shit happen here. No shortcuts on this)

Step 1. Sawcut the vertical line next to your house before you start breaking it on both sides of the wall. Clean lines are nice, and the diamond blade will go through the rebar fine. KEEP A STREAM OF WATER FLOWING ON THE BLADE AT THE CUT TO KEEP CONCRETE DUST DOWN AND YOUR BLADE COOL. VERY IMPORTANT. Concrete dust in your lungs can kill, this is why you need the proper respirator, not a cheap dust mask.

Step 2. Jackhammer wall until desired effect is achieved.

Step 3. (optional) smooth out wall face with angle grinder

Assume the job will take at least 1.5 manhours per cubic foot. I estimate work at 1 mhr/cf for union laborers who do this every day.

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And here's why the other ideas are bad:
Sledge hammer--You'll need some meth to get this done quickly, and meth is bad
Hammer drill--same as above, with a little relief
Concrete saw--concrete weighs 150 lbs/cubic foot. That wall weighs 400-600+ lbs looking at it, plus some foundation. You're not lifting that without equipment
Expansive clay is excellent in non-reinforced applications like granite, or concrete without rebar. Not very effective in reinforced concrete.
-------------------------------------------------------------

Redneck method:

Drill a couple expansive anchors into the top
Sawcut connection to wall (all the way through if possible)
Lift with engine hoist and roll to the truck/dumpster. Hit concrete with sledge near the sawcut line to get it to release and hope the rebar doesn't go into the house foundation.

Alternate to final step: connect to truck hitch and drag out like a tree stump. Hope you don't pull the house over. Record everything for youtube.

[Boissal]

Thanks for the replies!

DJ Sapp, you're saying I can make the wall cut with a simple skill saw assuming I have a decent diamond blade? I'd be worried about not going deep enough with a small blade.
I was looking at renting the concrete saw for that purpose since it should have built-in cooling (I was thinking of renting this: http://www6.homedepot.com/tool-truck...6_Gas/3512433/), will pack more punch and the blade is large enough that I should be able to separate the wall from the house in one cut.
As for the size of the chunks, I was envisioning multiple cuts to give me small manageable pieces, not necessarily getting the whole wall down in one part. If I ran 3 vertical cuts and a couple of horizontal I may not need the jackhammer? Again, what's left on the ground isn't too concerning to me as I plan on hiding it all under a deck.

Good beta on the respirator though, I just drilled a bunch of holes in volcanic rock and it was generating way more dust than usual, I was getting seriously concerned.

[DJSapp]

Thanks for the replies!

DJ Sapp, you're saying I can make the wall cut with a simple skill saw assuming I have a decent diamond blade? I'd be worried about not going deep enough with a small blade.
I was looking at renting the concrete saw for that purpose since it should have built-in cooling (I was thinking of renting this: http://www6.homedepot.com/tool-truck...6_Gas/3512433/), will pack more punch and the blade is large enough that I should be able to separate the wall from the house in one cut.
As for the size of the chunks, I was envisioning multiple cuts to give me small manageable pieces, not necessarily getting the whole wall down in one part. If I ran 3 vertical cuts and a couple of horizontal I may not need the jackhammer? Again, what's left on the ground isn't too concerning to me as I plan on hiding it all under a deck.

Good beta on the respirator though, I just drilled a bunch of holes in volcanic rock and it was generating way more dust than usual, I was getting seriously concerned.

Cutting with a skill saw will only get you 2" deep on each side, and I would guess that wall is 6-8" thick. It's not enough to go through, but it will protect your house foundation by cracking on the skinny bit of concrete left between the cuts when you hammer it. I wouldn't go too expensive on the diamond blade, unless you have a lot of other stuff you're going to do with it. Grind or bush the last bit down with an angle grinder or chipping gun with a bushing head.

I wouldn't recommend doing horizontal wall cuts without a track mounted saw. It is pretty easy to bind your blade when you get tired, and your body position is pretty jacked up to even do that in the first place. Pushing a saw through concrete isn't easy or fast, so I don't think cutting it into manageable bits will save you any work instead of hammering. When hammering, use the weight of the tool to do the work. You don't need to push it, you just lift it back up to the next area. It is not as hard as it sounds. You want this: http://www6.homedepot.com/tool-truck...ectric/HM1810/

As for the respirator, google silicosis. Have nightmares. Get a respirator that fits (ie seals airtight when you plug the hole) and has the proper filter cartridges.

[Boissal]

Thanks man! I'll go the route you suggest and only rent the jack + buy a decent blade.
I've worked for 10+ years in a chemistry lab where we handle ultra high purity silica gels and that stuff has been scaring the piss out of me for as long as I've been there. We have a legit respirator but the recommendation has always been to be in and out of the room within a minute or so and hold our breath. The people who manufacture that stuff have scuba equipment in the packaging room...

[DJSapp]

For the money, it may still be worth it to rent the big chop saw. Reason being if they drilled the rebar into the existing foundation, the skill saw isn't going to reach it, and it's going to be a bear to get it flush with the wall.

[old goat]

The sledge hammer works pretty well.

[sfotex]

I had some reinforced concrete cut last summer and it was like $150 (and that was just the minimum hourly rate..). the guy spent 15 mins cutting. I bet you can get that chucked into 4+ pieces for that price and your pretty much done...

[farmer]

That breaking foam you mentioned in the op is pretty cool stuff. You would need a hilti, and need to drill a lot of holes angled downhill enough to pour the foam into. You won't get the straight cut a saw would make, but it will break relatively "straight" b/w holes.

That still wouldn't deal with the steel, but I've been waiting for an excuse at work to use that breaking foam. I just need a case that is too delicate for regular explosives.

[old goat]

they used the breaking foam on some large granite boulders in our yard. I believe it's a) pretty expensive b) pretty particular about how it's used and c)--granite splits because of its crytalline structure. I wonder if it would work on concrete--especially reinforced where the rebar will keep cracks from spreading. Maybe someone here has used it for that.

[farmer]

I'm pretty sure the demo video I saw for it had several examples in concrete.

There is nothing special about granite that would make it break via any different mechanism than concrete (yes, I am fully aware about different UCS and other properties). It will crack between free faces. You would need to drill the holes such that the next hole is the best free face to break to.

The pics didn't load for me earlier. I was expecting a bigger wall. Rent the saw, make the vertical cut, then man the fuck up and smash it out. Dig down on either side and you don't have to worry about making a horizontal cut.

[Cruiser]

I can't support any solution that doesn't include a pickup truck and the phrase, "gun it!".

[::: :::]

I can't support any solution that doesn't include a pickup truck and the phrase, "gun it!".

& the requisite TR w/ drone POV

[Cruiser]

Damned right. Shoot, in the age of the interwebz, if you don't have someone around to hold your beer and the (remote control for the drone mounted) go-pro while you do something spectacular then it might as well not have happened.

[glademaster]

Damned right. Shoot, in the age of the interwebz, if you don't have someone around to hold your beer and the (remote control for the drone mounted) go-pro while you do something spectacular then it didn't happen.

FIFY

And go fuck yourself, character minimums.

[Boissal]

Turns out I don't have a hitch on the Subi or you guy's wishes may have been answered. The wall was actually poured along the foundation but wasn't attached to it so I skipped the saw.
I needed some time off from climbing to let a wrist heal up so I figured I might as well do more physical damage to myself before taking a break. Enter the sledgehammer.
It worked.



I may still need the jackhammer for the base of the wall, that part is stubborn.

[::: :::]

wham! bam!...as they say...