Joining new concrete to old

Discussion in 'Misc DIY' started by robgraham, Aug 10, 2006.

  1. robgraham

    robgraham Guest

    I'm adding a shed on the side of my garage.

    It works out that the new concrete floor level will just nicely line up
    with the top of one of the existing concrete steps into the garage -
    makes a nice reference point for the levelling.

    However the existing step has quite a 45 deg. bevel on it's leading
    edge. Do I need to treat this in any way to get the new concrete to
    bond to it ? My concern is that if the bond isn't reasonable, the new
    concrete will break away in time as it is potentially a weak spot.

    Thanks

    Rob
     
    robgraham, Aug 10, 2006
    #1
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  2. robgraham wrote:
    > I'm adding a shed on the side of my garage.
    >
    > It works out that the new concrete floor level will just nicely line up
    > with the top of one of the existing concrete steps into the garage -
    > makes a nice reference point for the levelling.
    >
    > However the existing step has quite a 45 deg. bevel on it's leading
    > edge. Do I need to treat this in any way to get the new concrete to
    > bond to it ? My concern is that if the bond isn't reasonable, the new
    > concrete will break away in time as it is potentially a weak spot.
    >
    > Thanks
    >
    > Rob
    >

    Its never a bad idea to chisel some slots and install some sort of metal
    ties in.
     
    The Natural Philosopher, Aug 10, 2006
    #2
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  3. robgraham

    Phil L Guest

    robgraham wrote:
    > I'm adding a shed on the side of my garage.
    >
    > It works out that the new concrete floor level will just nicely line
    > up with the top of one of the existing concrete steps into the garage
    > - makes a nice reference point for the levelling.
    >
    > However the existing step has quite a 45 deg. bevel on it's leading
    > edge. Do I need to treat this in any way to get the new concrete to
    > bond to it ? My concern is that if the bond isn't reasonable, the new
    > concrete will break away in time as it is potentially a weak spot.


    A 45 degree bevel on a step? - are you sure it's not just a kerbstone laid
    flat on it's back?
    Either way, you can't 'chamfer' concrete in this way, you are right to
    assume that it will crack up, the only way to stop this is to give it more
    depth, IE cut out a straight line with a grinder and chisel off an inch or
    two in depth, treat with neat PVA prior to concreting and scrape some slop
    into it.
     
    Phil L, Aug 10, 2006
    #3
  4. robgraham

    robgraham Guest

    Phil L wrote:

    > A 45 degree bevel on a step? - are you sure it's not just a kerbstone laid
    > flat on it's back?
    > Either way, you can't 'chamfer' concrete in this way, you are right to
    > assume that it will crack up, the only way to stop this is to give it more
    > depth, IE cut out a straight line with a grinder and chisel off an inch or
    > two in depth, treat with neat PVA prior to concreting and scrape some slop
    > into it.


    Yes a chamfer would have been a better word; when I cast the steps some
    25 years ago I obviously put a chamfer on the leading edges so that
    they wouldn't chip. OK I'll now have to cut it out !! Thanks for the
    advise.

    Rob
     
    robgraham, Aug 10, 2006
    #4
  5. robgraham

    Paul Hodges Guest

    I did something similar 10 years ago.....

    Footings to my garage are a metre wider than the garage (raft foundation).
    My new block built shed was to be roughly 8' wide so needed footings that
    reached beyond the scope of the garage foundations.
    I got two great lengths of angle iron, bent them into large V shaps and
    bolted them to the side of the footings.
    Then I poured the concrete - angle iron was then submerged in concrete.
    OK, no 45 degree thing going on, but that new groundwork has never moved a
    milimeter in 10 years.

    Hope that helps

    Regards
    Paul



    "The Natural Philosopher" <> wrote in message
    news:...
    > robgraham wrote:
    >> I'm adding a shed on the side of my garage.
    >>
    >> It works out that the new concrete floor level will just nicely line up
    >> with the top of one of the existing concrete steps into the garage -
    >> makes a nice reference point for the levelling.
    >>
    >> However the existing step has quite a 45 deg. bevel on it's leading
    >> edge. Do I need to treat this in any way to get the new concrete to
    >> bond to it ? My concern is that if the bond isn't reasonable, the new
    >> concrete will break away in time as it is potentially a weak spot.
    >>
    >> Thanks
    >>
    >> Rob
    >>

    > Its never a bad idea to chisel some slots and install some sort of metal
    > ties in.
     
    Paul Hodges, Aug 10, 2006
    #5
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