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  1. #1
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    Default Breaking up concrete

    Dear all,

    While digging for one of the posts for my gate, I noticed about 250 mm deep that there was concrete. More digging and I could see that it was an old slab. I wanted to put my post to be at least 300 into the ground but the concrete was resilient. First I tried the crowbar,it didn't do much. Then I tried an air chisel, that did even less, then a masonry bit in a hammer drill, that didn't do much either. A jack hammer would do the job but I thought hardly worthwhile for a little bit of concrete.

    So my question is for small areas of concrete what do you guys do? Assuming that you don't run out and hire a jack hammer, what sort of tools do you use?

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  3. #2
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    Default

    A combination of crow bar, elbow grease and sweat.

    The good news it it's probaly only 150mm thick max.

    When I was a boy I used to dig holes by hand, OK crow bar through solid rock, 900mm deep. :eek: Unfortunately that's not a fib.
    Boring signature time again!

  4. #3
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    Does your crowbar have a motor in it? Seriously, which end of the crowbar and how heavy. I reckon the slab I've got would be 150 and the crowbar was barely denting it.

  5. #4
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    Use the sharp end, and the only moter it had was the purr of a virile young bloke.
    Hang in there, you will fracture the concrete after a little while. Then its all over.
    Boring signature time again!

  6. #5
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    How about you come and show me and I'll take notes.

  7. #6
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    Quote Originally Posted by Tiger
    How about you come and show me and I'll take notes.
    Absolutely, no problems. You may not like the remuneration package I have worked out for you, but hey, if your'e happy to pay, I'm happy to break.
    Boring signature time again!

  8. #7
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    Default

    By the way Al, what do you do for a living?

  9. #8
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    Default

    Tri-Nitro-Toluene will do the trick. Very easy too.

  10. #9
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    Default

    Quote Originally Posted by Tiger
    By the way Al, what do you do for a living?
    star.

    Al

  11. #10
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    Default

    Well that explains the picture, the years haven't been good to you, my friend. But gee you look a lot like that guy who used to be on tv.

  12. #11
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    Go and spend ~$80 on one of those SDS rotary hammer drills (not a ordinary drill which hammers) and drill some holes through it.
    Turn the rotary action off and put a chisel in and break it up.


    OR

    Sit the post on the slab and bolt it down with some bracket dynabolted to the concrete. Possibly the easiest and strongest.

  13. #12
    Join Date
    May 2005
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    Turramurra, NSW
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    Default

    Tiger


    Suggest you get creative and save the blisters.
    You're digging a hole to give a solid foundation to your post. You just hit a 150mm slab which is a far more solid foundation than you're ever gonna make. Us the slab to secure your post. If you intended setting in concrete, rough up and key the slab, maybe drill some holes and shove in 150mm nails, drill reciprocal holes into your posts, concrete a collar around.

    Betcha this post will outlast the other.
    Bodgy
    "Is it not enough simply to be able to appreciate the beauty of the garden without it being necessary to believe that there are faeries at the bottom of it? " Douglas Adams

  14. #13
    Join Date
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    Yep...Go for a SDS Rotary Hammer.

    It will give you an excuse to buy a new toy.

    Said with big round doe eyes to the old woman...."Honey...If you want the gate up, I really really really need a SDS"


    Hooroo.
    Regards, Trevor.
    Grafton

  15. #14
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    Default

    Tiger,

    I'd also use a rotary hammer. I bought the $98 GMC version (with 20ish bits and 3 chisels), and it's a surprisingly good tool. Heavy, but effective.


    David

  16. #15
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    Any excuse to buy a new toy. Wondering though, what limits are there on these rotary drills? Will they be able to break up a square metre worth of concrete or is it a job for a jack hammer? Have seen rotary drills for around $70 or $80 at Bunnies which were supposedly trade quality, think it was Wagner brand, anyone bought one?

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