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Thread: Concrete slab expansion joints

  1. #1
    Senior Member Quattromike's Avatar
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    Concrete slab expansion joints

    We're planning a bit of concrete in our yard before it gets too cold approx 22Mx15M and was wandering what everyone uses for making expansion joinst or joint fillers?
    25mm mdf board would rot away and i cant seem to find where to get foam strip for the joints. Anyone?

  2. #2
    Senior Member Quattromike's Avatar
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    Re: Concrete slab expansion joints

    Hmm, not a lot of options then.

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    Re: Concrete slab expansion joints

    We used fabricated plastic section which acts also as shuttering, was quite expensive for what it was, but was pleased with end result
    BW

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    Re: Concrete slab expansion joints

    Cut a slot with a disc cutter every 5 mtrs to about half the depth of the concrete before it has cured and fill with mastic, easy cheap and effective

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    Re: Concrete slab expansion joints

    Quote Originally Posted by robs1 View Post
    Cut a slot with a disc cutter every 5 mtrs to about half the depth of the concrete before it has cured and fill with mastic, easy cheap and effective
    That would work as a contraction joint but won't fulfil the job of an expansion joint as I understand it?

    You can get an expansion joint thing which is supposedly a non rotting version of your MDF, can't remember what it is called though. We've got some lying around so I'll see if it still has a name on it.
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    Re: Concrete slab expansion joints

    Quote Originally Posted by bluewurzel View Post
    We used fabricated plastic section which acts also as shuttering, was quite expensive for what it was, but was pleased with end result
    BW
    I've seen those advertised by Travis Perkins and such like, it looks like a great idea if more expensive than steel shuttering. How easy was it to set and work with?
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    Re: Concrete slab expansion joints

    Very easy to set up, just wedge it up with bricks/hardcore and set it with blobs of concrete to the levels required. We used
    roller striker which made a quick and easy job, but as always preparation is the key
    bw

  8. #8
    Senior Member Quattromike's Avatar
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    Re: Concrete slab expansion joints

    I like the idea of expansion/shutter plastic boards. I've tried looking at all the websites but can't see what I'm looking for. I guess I'll have to go old school and pick up the phone and ask them, will try travis Perkins or keithbuilders next week.

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    Re: Concrete slab expansion joints

    Quote Originally Posted by Quattromike View Post
    I like the idea of expansion/shutter plastic boards. I've tried looking at all the websites but can't see what I'm looking for. I guess I'll have to go old school and pick up the phone and ask them, will try travis Perkins or keithbuilders next week.
    This is the stuff that Travis Perkins have flyers for: K-Form
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  10. #10
    Senior Member Quattromike's Avatar
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    Re: Concrete slab expansion joints

    The kform stuff is 18 for 3M length, it looks simple to use but how much time do you save above shuttering an putting in bitumen boards after

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    Re: Concrete slab expansion joints

    My concrete is in about 5 to six weeks it's about 40m by 25m with no expansion joints. Is my only option to use a con saw and cut half way thru and fill cuts with hot bitumen? What size sections do I need cut? Thanks in advance.

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    Re: Concrete slab expansion joints

    Quote Originally Posted by GALCAM View Post
    My concrete is in about 5 to six weeks it's about 40m by 25m with no expansion joints. Is my only option to use a con saw and cut half way thru and fill cuts with hot bitumen? What size sections do I need cut? Thanks in advance.
    I'd think the best option is the saw as you say. We usually cut to about 2 - 3" in a 6" slab but don't fill the cuts with anything, we've never seen anything crack with frost or anything as a result.

    If you've laid two slabs side by side the joint between the two counts as an expansion/contraction joint in one direction so you're only cutting long slabs. We usually cut at about 6m intervals, not sure what the correct distance is though. This link has more info, looks like we may be a bit long with our spacing.
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    Senior Member Quattromike's Avatar
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    Re: Concrete slab expansion joints

    Quote Originally Posted by Quattromike View Post
    The kform stuff is 18 for 3M length, it looks simple to use but how much time do you save above shuttering an putting in bitumen boards after
    We used the K-form shutter system in the end and it worked a treat. Set it up either Side of the panel and pour in the concrete and run a roller striker over it and left a good finish, a quick run over with the bull float and hey presto
    "At the end of the day, I think it's going to get very dark."

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