Concrete cancer

Discussion in 'Property Investment - Other' started by ritchie77, 21st Jun, 2015.

  1. ritchie77

    ritchie77 Member

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    Anyone have previous experience on subject matter? Balcony has considerable amount of wear and tear with concrete cancer from steel inside concrete.... Not sure how bad it is but probably unsafe and easy to fix for a builder of some sort. I have some pics I will try and download and wondering if this can be fixed via patching if some sort of builders can do this or it has to be fully replaced if dangerous for tenants. Looking for some experienced advice before tackling builders/trades for quotes and if it actually needs replaced in full?
     
  2. norwoodman

    norwoodman Member

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    Concrete cancer (spalling is the correct technical term) isn't usually unsafe unless left to deteriorate to a situation such that it becomes widespread in the steel reinforcing. It's caused by insufficient concrete cover to the steel reinforcing, which results in the steel corroding and expanding, which then pushes the surrounding concrete off.

    In most cases, it is repairable - but it becomes the case of replacing corroded steel, removing moisture and contaminants, and applying new concrete/grout appropriately otherwise it will happen again.
     
  3. jerrybee

    jerrybee Member

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    In the 60's or 70's to cut costs, some dodgy builders in Hong Kong used sea water to mix up the concrete. Hilariously sad stuff.
     
  4. Scott No Mates

    Scott No Mates ...and people wonder why?

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    Extent of damage will determine what remedial work needs to be done. Damage will vary depending upon how long it has been there. Contact a structural engineer for specific advice.
     
  5. ritchie77

    ritchie77 Member

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    Hi guys, pic attacthed.... This prob goes on for a few metres underneath, thoughts on how bad/easy to fix? Builders will obviously tell how much $ if/when need fixed.
     

    Attached Files:

  6. jerrybee

    jerrybee Member

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    Are you near the coast?
     
  7. ritchie77

    ritchie77 Member

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    Nope... Western suburbs but high up and windy?
     
  8. ritchie77

    ritchie77 Member

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    No response jerrybee -does that mean u think it's really bad lol....
     
  9. jerrybee

    jerrybee Member

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    No no I was just curious. I figured this would be more likely along the coast so I was surprised to see this is way inland. I'm no expert but it doesn't seem to bode well for you if you're not near salty water / winds and it's still got concrete cancer.
     
  10. WattleIdo

    WattleIdo Member

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    Have all you guys signed up on property chat? Come on, it's easy.
     
  11. ritchie77

    ritchie77 Member

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    Not yet but will get there... Still time until July 1st lol?
     
  12. handyandy

    handyandy Member

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    Looks pretty serious from the limited picture supplied.

    We have done extensive concrete cancer repairs and they didn't look as serious to start as you pic.

    It is very expensive to fix as all the rusted rods need to be fully exposed and cleaned up or removed and replaced.

    We have spent an inordinate amount of time on these jobs to end up with the area just looking 'normal'. So, massive effort spent no visual and rental improvement results.

    Best to talk to someone like

    http://www.remedial.com.au/structural-repairs/concrete-cancer

    as they can give you some idea on the scale.

    Not sure whether this is a multi story building or separate townhouse type structure as I can see some sort of steel (rusted) lintel. These would not normally be used in a concrete and brick structure.

    We have had previous discussions about concrete cancer so you might want to do a search and recap with those posts.

    Cheers
     
  13. Scott No Mates

    Scott No Mates ...and people wonder why?

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    Needs a good dose of chemo.

    Damage appears to be extensive due to the lack of cover. Repair will entail repropping the slab while the old rusted reo is exposed/treated/cut out, new reo tied in place and concrete sprayed over the soffit (shotcrete) alternatively kevlar bandages may be applied. An engineer must be engaged for the design.

    Is it on a unit? Then it is the responsibility of the body corporate.
     
    Last edited: 21st Jun, 2015
  14. ritchie77

    ritchie77 Member

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    Not unit... Also this particular part of the balcony is not essential nor is it supporting anything else so maybe just knock down and cut off and leave other end where damage ("cancer") stops.... Or maybe easier to tear all down and replace with smaller metal one of some sort? Yep going to need some expert advice but good to get some expert views here and also looking back on other posts. Thanks andy :)
     
  15. Scott No Mates

    Scott No Mates ...and people wonder why?

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    How old is the building? The RSJ will also need some attention - shot blasting to get back to raw metal, rust converter, ROZC etc too.
     
  16. handyandy

    handyandy Member

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    Is it possible to get some perspective shots to get a visual of what it is.

    Sounds like its just an awning rather than an actual balcony.

    Unfortunately even if you were to cut if off the rust will have gone further than the damage you can see.

    If you had clean concrete rather than the skimcoat then you could most probably see minute cracks. These minute cracks indicate rust that is starting to happen where it hasn't busted out as yet.


    We chased a lot of these tiny cracks and found rods with surface rust from minor to not so minor. All had to be cleaned.


    Cheers
     
  17. nww

    nww Member

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    There a few pics on here somewhere , pops up frequently about how the poster repaired a unit balcony.
     
  18. Schpeet

    Schpeet Member

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    I'm currently working on a concrete cancer repair project (civil engineer), but on a massive scale, talking many millions! Anyway, very hard to know from the very limited information provided and can't see much from the pictures posted however what others have said is spot on - the corroded reo will need to be removed and the only way to do that is to jackhammer out the concrete, cut out reo, weld new reo into place and patch with grout. It's impossible to know what extent of reo is affected until you start breaking out though. The treatment method you use depends on the extent of damage and the cause of the damage - will you need to do preventative maintenance works to minimise future damage? Also what are the access conditions like? I assume you will need some sort of scaffolding, and possibly a blasting/painting containment as well since that beam will need treatment (and possible replacement??).

    Your best bet would be to get a structural engineer out to inspect and provide a short report with treatment options and an estimate of repair costs.
     
  19. ritchie77

    ritchie77 Member

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    thganks guys, there is some access but will be tight.... (no room for a skip).

    Any recommendations for structural engineer specialising in this area.
     
  20. nww

    nww Member

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    Actually if you look at Handyandys pics you will see a section under concrete cancer.