My new (1950s) house has large -- e.g., one is 3.5 feet by 8.5 feet by 5 inches -- concrete slabs in our back yard. I'd like to remove them but don't know which tool(s) to use. Could this be done with a sledgehammer (in, say, an afternoon), or do I need a breaker hammer or the like?

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    Rough calculation - this will weigh close to a ton (literally, not figuratively). So hauling it away may not be so easy. – manassehkatz Apr 23 at 19:20
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    If you are certain you want to remove it, I would suggest spending a few minutes with a sledghammer, eye and ear protection banging away near a corner, just to get a feel for how it's built and how hard it will be to take apart. There may or may not be reinforcing steel, it may or may not be a consistent thickness - home concrete work is all over the map. If you chew off a foot or so at the corner, you'll have a much better idea of what you are going to be up against, and that will help you to choose your methods going forwards. – Ecnerwal Apr 23 at 20:17
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    you can drill pilot holes with a hammer drill to encourage fault lines that reduce it to manageable chunks, making a sledge much easier and more predictable. you can also use fire or ice to damage the slab, depending on the season. fire is set underneath, like a medieval castle siege. ice is used in winter with a drill and slightly salty water. Lastly, if you can pry/jack up a corner of the slab, it's under-support will be gone, and it will be easier to fissure with impacts. – dandavis Apr 25 at 18:34

What you have is a concrete slab not a block. Semantics. I would rent a jackhammer, breaking that thing up with a sledgehammer will be a arduous task. You may also need an angle grinder with a metal cut off wheel to cut the metal lath or rebar reinforcement’s that should be inside the slab. You will want to break it down into small enough pieces to lift and handle in order to make the disposal job easier.

  • Thanks -- updated the question with the correct terminology. – calcium3000 Apr 23 at 20:05

There are a whole spectrum of tools that might be useful for breaking concrete. It's hard to guess which one will be "just enough" to get the job done because there are several things that can affect the strength of the concrete:

  • how much cement was used in the mix
  • how the cure was carried out
  • size of aggregates
  • whether there's any embedded reinforcing steel, and what size

That said, if you're determined to have it out one way or another, you can certainly start small and escalate if you're not satisfied with the rate of progress.

One thing that can really help particularly when using hand tools is to get the concrete lifted off the soil. Concrete cracks much more easily when it's not well supported. Remove soil under one edge of the concrete enough to insert a hydraulic jack (bottle jack, automotive floor jack, etc) under the slab a few inches from its edge. Raise the slab an inch or more off the soil, then start striking the surface of the slab. Use at least an 8 pound hammer. Eventually it'll crack.. or you'll decide to go to the tool rental center and either an electric demolition hammer or a pneumatic jackhammer.

If the slab can be raised several inches at one of the narrow sides and you can start the breaking at the opposite side then you may get away with jacking up the slab in just the one place. When the pieces are broken to where they weigh just a few hundred pounds the raising can be done with a shovel or other prying tool instead of the hydraulic jack.

  • I'll give that a shot. In my second picture one of the slabs is being lifted by the root of a large honeylocust tree. – calcium3000 Apr 24 at 11:42
  • start small and escalate, +1. Some concrete laughs at your hammer. Some of it, you'll wonder why walking on it hadn't caked it yet. Start in the corner. Removing your spoils immediately to make room for where the next fissure will slide the next chunk over to also helps. – Mazura Apr 25 at 2:10

I did something similar a few years ago with a 12lb sledgehammer. Best/worst workout I ever got. Was about 12x12 and about 4" thick with the rebar laying on the bottom of the cement and not in the middle like it was supposed to be (that was nice). To make it simpler I rented a cement saw for the day and cut 2" deep cuts into the pad up like a checkers board. Dug under the cement a bit with a pick and then wailed on the cement. Nice chunks would break off and then repeat. Took about a week to do. I'll never do it again with a sledgehammer. If I ever, hope I never, need to do it again I'll rent a jackhammer. I paid someone to come haul it off.

  • I could break that up with a sledge in 20 minutes. Paying someone else to haul it away which takes all day: priceless. – Mazura Apr 25 at 2:06

The slab is probably only that thick at the edge. What I have done in the past for slabs that did not have reinforcements like wire mesh or rebar, was to pry 1 edge up then a 20 lb sledge hammer or better yet a 35 lb lead cannon ball slammed down the concrete breaks up quite nicely even at 4+ inches. If there is wire my best advice would be to rent a saw and cut it but only 2 of the residential slabs I have removed have had wire the first one I tried to break up until finally giving up and renting a saw the second one as soon as I realised it had wire I went and got a saw. I find a 4x4 or 3" piece of conduit is usually strong enough to slightly lift a edge of a slab , you don't need much and it will make the demo much easier, yes you can bust up concrete with out lifting it but it will go 100 times faster with a slight air gap below. My son and I took out a 20x 40 slab in about 6 hours using this method.

  • Maybe I'll start with my 20 lb kettlebell -- could even make a workout out of it. – calcium3000 Apr 25 at 14:37

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