Breaking up small concrete slabs (5m x 5m)

[SteveAndBelle]

Hi,

I've got a couple of smallish (approx 5m x 5m) concrete slabs in my backyard left by previous owners over the last 90 odd years and I'm wanting to remove them. One is a dodgy looking slab that looks as though was used as a BBQ area at one point and the other is a slab still covered by a crappy old shed which I'll be removing within the next 12-18 months.

As these are the only slabs I've got to break up & remove I was just going to hire an electric jack hammer however I then realised you can buy generic Chinese copies of decent Japanese branded (Hitach & Makita) electric Jack Hammers for around the $350-$400 mark which is abotu the same as a couple of weekends worth of hire. Looking further again I realised that I can pickup a 2nd-hand 1500W Hitachi jack hammer in good condition for around about the same price.

I'm tempted to get the 2nd-hand Hitachi over the new Chinese copies however as I know nothing about Jack Hammers is there anything I should look out for when buying one (old and/or new) ?? Could a 1500W jack hammer actually do the job I require assuming the slabs are approx. 5-6 inches thick ?

Any comments suggestions are welcome, thanks !

[silentC]

Haven't you got a sledge hammer?

If you buy one, make sure you get a decent one like a Kango, not one of those little rotary hammer drills. You'd do just as well using a mash hammer and a cold chisel...

[SteveAndBelle]

SilentC, you seem to answer all my queries within minutes of me posting them ! It's great, thanks

Believe it or not I was considering using my sledgy to break the slab up as that's what my Dad used to do ... but forget that, I value my back too much and consider a few hundred bucks a good investment to save my time & sanity. I dunno how Dad did it that way ... and so many times too. Amazing.

Yeah, I've got a big fat Metabo rotary impact drill/jack hammer thingy and only bought it because I wanted to drill lots of low speed/high torque holes through big timber stumps & railway sleepers etc. plus to use the hammer & chisel action to remove tiles etc. I did try it on a few chunks of concrete just to see what it would do and you're right, it's basically useless however it's good for engraving your name in the footpath

The 2nd-hand Hitachi and the new Chinese copies are those 15-20kg two-handed jobbies and from what I can tell they're designed to break up concrete but I'm not too sure how well they do it that's all.

Steve.

[Buzzer]

Hi,

A sledge hammer would be the go (cheaper). That concrete sounds like it has some age on it. Meaning it probably won't be very thick and should (I say should) break up relatively easily due to its age(it probably has cracks all through it already). The job is half done for you before you even start!!!!

Good luck

[silentC]

I had a couple of big slabs in the backyard at Sydney. I broke the first one up with the sledgy. Then I hit the one that was poured on top of another one - 8"+ of concrete! Couldn't make a dent in it, so I got my wife's cousin to come in with his excavator and he picked it up at one corner, levered it out sideways and smashed it up with the bucket. We filled a 10 cubic metre bin with concrete, then another one the next weekend.

I suppose my point is this: what are you going to do with the concrete afterwards? You have to get rid of it and it would be a big job by hand, so maybe you should look at getting someone to come in and do it with the machines? It will cost more than buying the jack hammer, but then you have to dispose of the rubble afterwards, which will cost you as well. Then there's the time it will take to do it by hand.

I don't know a lot about electric jacks, apart from having spent a few hours weilding one. I've hired kangos in the past. They always seem to be leaking oil and the tips need regrinding a lot. So I'm not sure how much maintenance you'd be letting yourself in for. I suppose you could buy one, use it and then sell it. Would no doubt save you money over hiring one if you need to hire it over a couple of weekends.

[JDub]

I just busted up a small 1 x 3m slab (100 thick) with an electric jack hammer I borrowed from my BIL. took me about an hour to break it up

Im no expert (far from it ) but dont think it would take 4 days with a jack hammer to bust up the two small slabs you have. A full days hire should be plenty I reckon (break it up first take it away later). Just do em both on the same day if you want to save your coin

[Ian Smith]

Have to agree with JDub. I needed to bust out about 20 feet of pathway and a couple of pergola post supports. It was hand laid about 15 years previously, and over done at around 3- 4 inches thick. The neighbour kindly loaned me a sledgehammer, but after a couple of whacks it was pretty obvious I was going to buggered long before the path way was. I sent the eldest son down to Kennards and he come back with this bloody great electric beastie that needed it's own trolley to get around. I was beginning to think that maybe the sledgehammer was the way to go after all because it was a bit of a struggle to even lift the thing. Anyway I had paid for it (can't remember how much but I reckon I got change out of $100.00) I stood this thing up, pulled the trigger, and the concrete just fell apart - took about 20 mins to not only reduce the pathway to manageable bits but it just blew apart the post supports, and they were about 10 inches square and two feet deep - has to be the way to go

Ian

[SteveAndBelle]

Hmmm, now there's food for thought ! Thanks Ian & JDub.

A concern I have is that one or both slabs have been hand laid (I think the BBQ is definitely hand laid) and knowing how my Dad & I used to over-engineer everything we DIY'd I'm concerned that if I manage to get an entire day put aside for this and start with a sledgy to find out that the outside 4" edges turn into a 10" thick centre I wont be too happy.

Hmmmm. I'm really not keen on the sledgy idea however because I probably wont need a jack hammer after these two slabs maybe I should hire instead of buy. Hmmmmmm.

[woodsprite]

You have a garage in the yard - meaning you have access? If it was me, I'd get a bobcat in - breaks it up, digs it up, carts it away and smooths off the area afterwards. Arounf Bendigo a bobcat and tipper are anything from $65.00 to $80.00 an hour. Maybe 2 hours work for a bobcat? And the yard is cleaned up pretty well afterwards. May be worth thinking about - and you can sit back with a greenie and watch him at it!

Good luck with it - shifting concrete is blood AWFUL!

[SteveAndBelle]

Yeah, good idea Woodsprite. Yes, I do have very good access down the side of the house to the backyard where the two slabs are.

I might look into a bobcat as that does sound like a lot less hassle & effort on my behalf plus it's cheaper and I don't have to deal with the disposal to boot ! Once I no longer need the dodgy shed I can pull it down and get them back to rip that slab up too ... and it will still probably be cheaper than buying a jack hammer and doing it myself.

Now that's sounding a lot better I'll look into it anyway, thanks !

[silentC]

Hey, that was my idea!

The bobcat/tipper hire is only part of it though. You'll probably have to pay tip fees too.

[SteveAndBelle]

Whoops, sorry Silent, it was your idea first I didn't realise it was so inexpensive until Woodsprites post. For some reason I thought it'd cost at least $400 for something like that.

I'm still wading through the hundreds of Bobcat & Tipper hire places via Yellow Pages to find one in the local area. Once I've found one I'll give 'em a call.

[Bluegum]

SteveandBelle,

I work for an earthmoving company on weekends here in Ipswich. If you are thinkning about getting a bobcat in let me know and I will pass on the company details. I don't quote prices but the boss would contact you and discuss it.

[TEEJAY]

If you have access don't bother with a bobcat for breaking up concrete - use a backhoe - might cost you $5 or $10 an hour more and do it in a lot less time. A heavy machine will give much much quicker results - do the sums.

[tanii51]

spent 4 years with a demo copmpany breaking concrete ,, if it hasnt got any steel reinforcing use a crow bar to clear the base fill from a corner so theres nothing under neath ( only needs 1/2 an inch ) then hit the edge with the back end of the crow bar . it will crack some where then just lift it using the crow bar as a lever, a brick or bit of wood under neath will do til you can put a block under it then hit with back end of crow bar again . in sth oz its much cheaper to dispose of old concrete at dedicated recyling place s that specialize in concrete recycling than the normal dumps.
If its got rio in a jack hammer is the way to or a escavator / backhoe