How much can concrete be damaged before it is a problem?

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XC70
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Re: How much can concrete be damaged before it is a problem?

Post by XC70 »

Arcuarius wrote: Tue Apr 07, 2020 10:05
XC70 wrote: Sun Apr 05, 2020 22:27 Thanks for the info. So I assume it will have been inspected and be on a condition report somewhere? What happens when the chunk drops off, will it all come in one go or just slowly flake and turn to dust? Not sure I would want to be underneath if it came off in one go!
It had a principal inspection in early January:
Overall the structure was found to be in a reasonable condition, however several deck beams suffer varying degrees of spalling/hollow sounding concrete mainly at the centre of the bridge along the joint. Corrosion and calcite stains are noted at the affected areas as well as reinforcement suffering severe corrosion. A large amount of concrete was removed during the inspection. There are localised areas of spalled concrete to the parapets with reinforcement revealed suffering minor and moderate corrosion.
I don't have access to scheme programming or anything like that but I've worked on less damaged structures myself in the past. I'd be shocked if it wasn't in there somewhere.
Thanks for the information. Hopefully when the works start it won't restrict the use of the greenway. We have waited nearly 20 years for this amenity, so hopefully we won't lose the use for a period of works (HS2 is already proving to be enough of a threat...).

Thanks again
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Conekicker
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Re: How much can concrete be damaged before it is a problem?

Post by Conekicker »

Arcuarius wrote: Tue Apr 07, 2020 09:51
Conekicker wrote: Sun Apr 05, 2020 20:43 Area 7. Allow me to express my complete lack of surprise.
As someone that works in the structural design team in Area 7 - thank you for that...
We both know how slowly structures schemes progress. In my experience, 7 are slower than others, I've no idea why that is though. I heard the old, "We've got no money" tale just a little bit too often.

On the plus side, you're not Area 6.
Patience is not a virtue - it's a concept invented by the dozy beggars who are unable to think quickly enough.
darkcape
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Re: How much can concrete be damaged before it is a problem?

Post by darkcape »

XC70 wrote: Sun Apr 05, 2020 22:27 Thanks for the info. So I assume it will have been inspected and be on a condition report somewhere? What happens when the chunk drops off, will it all come in one go or just slowly flake and turn to dust? Not sure I would want to be underneath if it came off in one go!
Concrete cover (thickness from surface to first reinforcing bar) is generally 40-80mm, so when concrete breaks off it's generally small pebble sizes. Look on the hard shoulder beneath overbridges and you can sometimes see debris either in pebbles or crushed into dust by traffic.

There is always a risk of bigger lumps falling off but is quite rare - vehicle strikes cause worse damage more often.

Thanks for posting that excerpt Arcuarius - fairly typical the worst parts are along the joint, water running off the carriageway washing salt/grit, oil, acids etc from the carriageway above.
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Arcuarius
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Re: How much can concrete be damaged before it is a problem?

Post by Arcuarius »

Conekicker wrote: Tue Apr 07, 2020 20:19
Arcuarius wrote: Tue Apr 07, 2020 09:51
Conekicker wrote: Sun Apr 05, 2020 20:43 Area 7. Allow me to express my complete lack of surprise.
As someone that works in the structural design team in Area 7 - thank you for that...
We both know how slowly structures schemes progress. In my experience, 7 are slower than others, I've no idea why that is though. I heard the old, "We've got no money" tale just a little bit too often.

On the plus side, you're not Area 6.
The problem isn't at the design stage - we're constantly crying out for work to do but we're just being drip fed one or two minor schemes at a time.

Also I started out in Area 6, back in the day. It was a lot better then.
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nowster
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Re: How much can concrete be damaged before it is a problem?

Post by nowster »

KeithW wrote: Mon Apr 06, 2020 15:03 There are 2000 year old concrete bridges built by the Romans that are still in daily use ...
There could be an element of Survivorship Bias too.
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KeithW
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Re: How much can concrete be damaged before it is a problem?

Post by KeithW »

nowster wrote: Tue Apr 07, 2020 23:47 There could be an element of Survivorship Bias too.
Possibly but the greater likelihood is simply that the Romans were simply superb civil engineers. The survival of so many of the structures they built is testament to that. Hydraulic cement was not rediscovered until the 18th century which is also when innovators such as John McAdam and Thomas Telford started building really good roads again.

To give another example the Victorians made a big thing out of shipping Cleopatra's Needle , a 21 metre Egyptian Obelisk to London and reerecting it. The Romans shipped many to their capital including the 24 metre tall Flaminio Obelisk which was erected in the Circus Maximus in 10 BC.
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Conekicker
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Re: How much can concrete be damaged before it is a problem?

Post by Conekicker »

Arcuarius wrote: Tue Apr 07, 2020 23:21
Conekicker wrote: Tue Apr 07, 2020 20:19
Arcuarius wrote: Tue Apr 07, 2020 09:51
As someone that works in the structural design team in Area 7 - thank you for that...
We both know how slowly structures schemes progress. In my experience, 7 are slower than others, I've no idea why that is though. I heard the old, "We've got no money" tale just a little bit too often.

On the plus side, you're not Area 6.
The problem isn't at the design stage - we're constantly crying out for work to do but we're just being drip fed one or two minor schemes at a time.

Also I started out in Area 6, back in the day. It was a lot better then.
Like I said, cash. Folks need to try harder to get it at the VM stage.
Patience is not a virtue - it's a concept invented by the dozy beggars who are unable to think quickly enough.
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