On Saturday, June 26, 2021 at 9:38:32 AM UTC-4, Clive Arthur wrote:
> On 25/06/2021 17:23, Fred Bloggs wrote:
>
> <snipped>
> >
> > That big reinforcing shear wall disintegrated like it was made out of sand.
> >
> I wonder about the aggregate. There are cases where pyrites in the
> aggregate cause concrete to crumble and rebar to corrode. In the UK
> it's particularly prevalent in Cornwall where tin mine tailings were
> sometimes used in the aggregate on concrete block houses, they call it
> 'Mundic'.
>
> You can buy a cheap house in Cornwall if it's made from Mundic Block and
> you have cash - you won't get a mortgage. There are similar issues in
> the West of Ireland.

Good point. Aggregate and water contamination is a huge issue. The state of Connecticut is still dealing with a huge pyrrhotite contamination issue. The state set up a special agency using an insurance model to deal with paying for the time consuming and expensive repairs.
https://www.fema.gov/case-study/connecticuts-crumbling-concrete

In Florida seawater and salt contamination of concrete components a is major issue. They have gone so far as to develop a saltwater concrete which eliminates the problem. They have to use fiber reinforced rebar in this case, nothing else will do. The Ley video about the fiber rebar is total hysteria, they can do things like double the diameter of fiber rebar to get around that strain limitation and big cracks.
https://www.wlrn.org/news/2017-08-31/university-of-miami-researchers-present-the-worlds-most-interesting-concrete-and-rebar
And the sate already has several bridge, walkway and road projects using this material.
http://seacon.um-sml.com/
Salt contamination of aggregate and water used in the Champlain Towers construction most certainly could have accelerated its demise. The major inspection was due 20 years ago. This a real can of worms for the coastal cities in the state because you're looking at many billions of lost real estate value. People in Surfside area are already scared to death to remain in their seaside condos. I know some materials scientist or engineer saw this coming decades ago. But the development and profit fanatics would not be stopped..

>
> --
> Cheers
> Clive

On Saturday, June 26, 2021 at 10:31:15 AM UTC-4, bitrex wrote:
> On 6/25/2021 1:44 PM, John Robertson wrote:
> >
> > On 2021/06/25 9:23 a.m., Fred Bloggs wrote:
> >> On Friday, June 25, 2021 at 11:34:04 AM UTC-4,
> >> jla...@highlandsniptechnology.com wrote:
> >>> On Fri, 25 Jun 2021 07:29:09 -0700 (PDT), Fred Bloggs
> >>> <bloggs.fred...@gmail.com> wrote:
> >>>
> >>>> But that didn't do it. Uneven settlement creates internal stresses
> >>>> on the framing, and when the framing has internally disintegrated
> >>>> due to decades of corrosion from water damage, it lets loose suddenly.
> >>>> You don't see a bit of steel column or beam in the rubble because
> >>>> the building was 100% reinforced concrete- i.e. poured concrete with
> >>>> some rebar dropped in it. It was shear wall frame system, meaning a
> >>>> few external solid shear walls used to give the flimsy interior
> >>>> repetitive platforms structural stability. When the main shear wall
> >>>> collapsed, the flimsy 12-story repetitive platform tower teetered
> >>>> for a few seconds on its own before it totally collapsed. The condo
> >>>> was made of the cheapest construction in both materials and labor
> >>>> the law allowed at the time, really thin floors, walls and columns,
> >>>> a skimp job from start to finish. Combine this with minimal,
> >>>> slipshod maintenance, history of water leakage and observed
> >>>> corrosion, and low end inspections, and you end up with catastrophe.
> >>>> And to think right up to the end a 2-bedroom in this dilapidated
> >>>> hovel was selling for $700k.
> >>>> https://www.usatoday.com/story/news/investigations/2021/06/24/building-collapse-miami-structure-had-been-sinking-into-earth/7778631002/
> >>>>
> >>> Video:
> >>>
> >>> https://www.nbcmiami.com/news/local/video-shows-wing-of-surfside-condo-building-collapse-in-seconds/2479955/
> >>>
> >>
> >> That big reinforcing shear wall disintegrated like it was made out of
> >> sand.
> >>
> >> Several of the big contractors in the area who build these kinds of
> >> buildings are saying this looks exactly like corroded rebar failure.
> >> The original flimsy construction together with foundation settlement
> >> causes seams and cracks to open up at the intersections of the various
> >> structural planes allowing water to enter.
> >> https://www.fdot.gov/structures/innovation/frp.shtm
> >> I really doubt they used stainless steel rebar, and fiber reinforced
> >> rebar wasn't available at the time; AFAIK,
> >> Then recent research out of Northeastern University shows that because
> >> of the high CO2 levels in the air, reinforced concrete structural
> >> usable lifetime needs to be derated to 67% estimated.
> >> https://www.fastcompany.com/3037370/concrete-is-not-as-strong-of-a-building-material-as-we-thought
> >>
> >> This really goes after steel rebar.
> >> Rebar is hunky dory but it needs to be sealed up inside the concrete
> >> but good, good luck with that.
> >>
> >> The fallback excuse relying on "building codes" is a scam. Building
> >> codes at their minimums are criminally deficient, the reason being
> >> they are written by self-styled regulatory organizations controlled by
> >> the builders who fight any and everything that might add cost to the
> >> build.
> >>
> >>>
> >>>
> >
> > More likely the reason the rebar corroded (if that was indeed the cause)
> > was the close proximity to the ocean. Salt is extremely corrosive to
> > unprotected steel as anyone in the northern states or Canada can attest
> > with road salting ruining bridges and overpasses...
> >
> > You really have to connect climate change to everything, don't you -
> > everything is a climate tragedy!
> >
> > I suspect the building failed due to plain old fashioned human stupidity.
> >
> > Didn't these people do a periodic engineering structural analysis -
> > sometimes called a Depreciation Report? Oh, this is Florida...perhaps
> > they don't like government interfering very much with good ol'
> > enterprising folks?
> >
> > Read this (if you can - requires a subscription):
> >
> > https://www.academia.edu/7759895/The_Maintenance_of_Residential_Towers_in_Condominium_Tenure_A_Comparative_Analysis_of_Two_Extremes_Israel_and_Florida
> >
> >
> > Florida's condominium bylaws:
> >
> > http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=0700-0799/0718/0718.html
> >
> >
> > John
> It was inspected in 2018 and the company said the building was in pretty
> rough shape, which gave the owners time to find someone to pay off to
> say it was fine for the 40 year re-certification

Nah- all they noted was some superficial spalling and cracks, nothing structural, and the recommended action was cosmetic patching. The way they looked for anything serious was tapping the walls looking for voids- gimme a break. And the repirs coast they quoted were quite obviously a huge ripoff. Like $1M to strip that relatively small roof and lay down some cheap 10 year tar. All the numbers coming out of this state are ridiculous, the place is a ripoff.

On 2021/06/26 7:47 a.m., Fred Bloggs wrote:
> On Saturday, June 26, 2021 at 9:38:32 AM UTC-4, Clive Arthur wrote:
>> On 25/06/2021 17:23, Fred Bloggs wrote:
>>
>> <snipped>
>>>
>>> That big reinforcing shear wall disintegrated like it was made out of sand.
>>>
>> I wonder about the aggregate. There are cases where pyrites in the
>> aggregate cause concrete to crumble and rebar to corrode. In the UK
>> it's particularly prevalent in Cornwall where tin mine tailings were
>> sometimes used in the aggregate on concrete block houses, they call it
>> 'Mundic'.
>>
>> You can buy a cheap house in Cornwall if it's made from Mundic Block and
>> you have cash - you won't get a mortgage. There are similar issues in
>> the West of Ireland.
>
> Good point. Aggregate and water contamination is a huge issue. The state of Connecticut is still dealing with a huge pyrrhotite contamination issue. The state set up a special agency using an insurance model to deal with paying for the time consuming and expensive repairs.
> https://www.fema.gov/case-study/connecticuts-crumbling-concrete
>
> In Florida seawater and salt contamination of concrete components a is major issue. They have gone so far as to develop a saltwater concrete which eliminates the problem. They have to use fiber reinforced rebar in this case, nothing else will do. The Ley video about the fiber rebar is total hysteria, they can do things like double the diameter of fiber rebar to get around that strain limitation and big cracks.
> https://www.wlrn.org/news/2017-08-31/university-of-miami-researchers-present-the-worlds-most-interesting-concrete-and-rebar
> And the sate already has several bridge, walkway and road projects using this material.
> http://seacon.um-sml.com/
> Salt contamination of aggregate and water used in the Champlain Towers construction most certainly could have accelerated its demise. The major inspection was due 20 years ago. This a real can of worms for the coastal cities in the state because you're looking at many billions of lost real estate value. People in Surfside area are already scared to death to remain in their seaside condos. I know some materials scientist or engineer saw this coming decades ago. But the development and profit fanatics would not be stopped.
>
>

The strata council or homeowners may hold some responsibility. As I
said, the minutes of the past number of years would make for good
reading. If council knew, and had presented it to the owners at the AGM
and the owners voted it down or defer...

I hope the council minutes were stored off site, or filed with the state
government.

John

On Saturday, June 26, 2021 at 12:47:28 PM UTC-4, John Robertson wrote:
> On 2021/06/26 7:47 a.m., Fred Bloggs wrote:
> > On Saturday, June 26, 2021 at 9:38:32 AM UTC-4, Clive Arthur wrote:
> >> On 25/06/2021 17:23, Fred Bloggs wrote:
> >>
> >> <snipped>
> >>>
> >>> That big reinforcing shear wall disintegrated like it was made out of sand.
> >>>
> >> I wonder about the aggregate. There are cases where pyrites in the
> >> aggregate cause concrete to crumble and rebar to corrode. In the UK
> >> it's particularly prevalent in Cornwall where tin mine tailings were
> >> sometimes used in the aggregate on concrete block houses, they call it
> >> 'Mundic'.
> >>
> >> You can buy a cheap house in Cornwall if it's made from Mundic Block and
> >> you have cash - you won't get a mortgage. There are similar issues in
> >> the West of Ireland.
> >
> > Good point. Aggregate and water contamination is a huge issue. The state of Connecticut is still dealing with a huge pyrrhotite contamination issue. The state set up a special agency using an insurance model to deal with paying for the time consuming and expensive repairs.
> > https://www.fema.gov/case-study/connecticuts-crumbling-concrete
> >
> > In Florida seawater and salt contamination of concrete components a is major issue. They have gone so far as to develop a saltwater concrete which eliminates the problem. They have to use fiber reinforced rebar in this case, nothing else will do. The Ley video about the fiber rebar is total hysteria, they can do things like double the diameter of fiber rebar to get around that strain limitation and big cracks.
> > https://www.wlrn.org/news/2017-08-31/university-of-miami-researchers-present-the-worlds-most-interesting-concrete-and-rebar
> > And the sate already has several bridge, walkway and road projects using this material.
> > http://seacon.um-sml.com/
> > Salt contamination of aggregate and water used in the Champlain Towers construction most certainly could have accelerated its demise. The major inspection was due 20 years ago. This a real can of worms for the coastal cities in the state because you're looking at many billions of lost real estate value. People in Surfside area are already scared to death to remain in their seaside condos. I know some materials scientist or engineer saw this coming decades ago. But the development and profit fanatics would not be stopped.
> >
> >
> The strata council or homeowners may hold some responsibility. As I
> said, the minutes of the past number of years would make for good
> reading. If council knew, and had presented it to the owners at the AGM
> and the owners voted it down or defer...
>
> I hope the council minutes were stored off site, or filed with the state
> government.

The press is misreporting the structural issue found in an inspection. That issue was about waterproofing the deck holding the pool, all of which sat atop a garage. The pool and garage are intact and not involved in the collapse. The kind of defects that caused the collapse were hidden and not observable by usual means.
https://theconstructor.org/practical-guide/measure-reinforcement-corrosion-concrete/7712/

In the future, all buildings will be instrumented during construction so they can alert authorities to a problem. There's actually a technology that uses the cement as a battery to power the sensors. But that's way off in the future. Right now we're still in the stone ages because no one wants to pay for anything.

>
> John

On Saturday, June 26, 2021 at 12:47:28 PM UTC-4, John Robertson wrote:
> On 2021/06/26 7:47 a.m., Fred Bloggs wrote:
> > On Saturday, June 26, 2021 at 9:38:32 AM UTC-4, Clive Arthur wrote:
> >> On 25/06/2021 17:23, Fred Bloggs wrote:
> >>
> >> <snipped>
> >>>
> >>> That big reinforcing shear wall disintegrated like it was made out of sand.
> >>>
> >> I wonder about the aggregate. There are cases where pyrites in the
> >> aggregate cause concrete to crumble and rebar to corrode. In the UK
> >> it's particularly prevalent in Cornwall where tin mine tailings were
> >> sometimes used in the aggregate on concrete block houses, they call it
> >> 'Mundic'.
> >>
> >> You can buy a cheap house in Cornwall if it's made from Mundic Block and
> >> you have cash - you won't get a mortgage. There are similar issues in
> >> the West of Ireland.
> >
> > Good point. Aggregate and water contamination is a huge issue. The state of Connecticut is still dealing with a huge pyrrhotite contamination issue. The state set up a special agency using an insurance model to deal with paying for the time consuming and expensive repairs.
> > https://www.fema.gov/case-study/connecticuts-crumbling-concrete
> >
> > In Florida seawater and salt contamination of concrete components a is major issue. They have gone so far as to develop a saltwater concrete which eliminates the problem. They have to use fiber reinforced rebar in this case, nothing else will do. The Ley video about the fiber rebar is total hysteria, they can do things like double the diameter of fiber rebar to get around that strain limitation and big cracks.
> > https://www.wlrn.org/news/2017-08-31/university-of-miami-researchers-present-the-worlds-most-interesting-concrete-and-rebar
> > And the sate already has several bridge, walkway and road projects using this material.
> > http://seacon.um-sml.com/
> > Salt contamination of aggregate and water used in the Champlain Towers construction most certainly could have accelerated its demise. The major inspection was due 20 years ago. This a real can of worms for the coastal cities in the state because you're looking at many billions of lost real estate value. People in Surfside area are already scared to death to remain in their seaside condos. I know some materials scientist or engineer saw this coming decades ago. But the development and profit fanatics would not be stopped.
> >
> >
> The strata council or homeowners may hold some responsibility. As I
> said, the minutes of the past number of years would make for good
> reading. If council knew, and had presented it to the owners at the AGM
> and the owners voted it down or defer...
>
> I hope the council minutes were stored off site, or filed with the state
> government.
>
> John

https://www.anthropocenemagazine.org/2021/05/74784/

On Fri, 25 Jun 2021 10:44:17 -0700, John Robertson <spam@flippers.com>
wrote:

>
>On 2021/06/25 9:23 a.m., Fred Bloggs wrote:
>> On Friday, June 25, 2021 at 11:34:04 AM UTC-4, jla...@highlandsniptechnology.com wrote:
>>> On Fri, 25 Jun 2021 07:29:09 -0700 (PDT), Fred Bloggs
>>> <bloggs.fred...@gmail.com> wrote:
>>>
>>>> But that didn't do it. Uneven settlement creates internal stresses on the framing, and when the framing has internally disintegrated due to decades of corrosion from water damage, it lets loose suddenly.
>>>> You don't see a bit of steel column or beam in the rubble because the building was 100% reinforced concrete- i.e. poured concrete with some rebar dropped in it. It was shear wall frame system, meaning a few external solid shear walls used to give the flimsy interior repetitive platforms structural stability. When the main shear wall collapsed, the flimsy 12-story repetitive platform tower teetered for a few seconds on its own before it totally collapsed. The condo was made of the cheapest construction in both materials and labor the law allowed at the time, really thin floors, walls and columns, a skimp job from start to finish. Combine this with minimal, slipshod maintenance, history of water leakage and observed corrosion, and low end inspections, and you end up with catastrophe.
>>>> And to think right up to the end a 2-bedroom in this dilapidated hovel was selling for $700k.
>>>> https://www.usatoday.com/story/news/investigations/2021/06/24/building-collapse-miami-structure-had-been-sinking-into-earth/7778631002/
>>> Video:
>>>
>>> https://www.nbcmiami.com/news/local/video-shows-wing-of-surfside-condo-building-collapse-in-seconds/2479955/
>>
>> That big reinforcing shear wall disintegrated like it was made out of sand.
>>
>> Several of the big contractors in the area who build these kinds of buildings are saying this looks exactly like corroded rebar failure. The original flimsy construction together with foundation settlement causes seams and cracks to open up at the intersections of the various structural planes allowing water to enter.
>> https://www.fdot.gov/structures/innovation/frp.shtm
>> I really doubt they used stainless steel rebar, and fiber reinforced rebar wasn't available at the time; AFAIK,
>> Then recent research out of Northeastern University shows that because of the high CO2 levels in the air, reinforced concrete structural usable lifetime needs to be derated to 67% estimated.
>> https://www.fastcompany.com/3037370/concrete-is-not-as-strong-of-a-building-material-as-we-thought
>> This really goes after steel rebar.
>> Rebar is hunky dory but it needs to be sealed up inside the concrete but good, good luck with that.
>>
>> The fallback excuse relying on "building codes" is a scam. Building codes at their minimums are criminally deficient, the reason being they are written by self-styled regulatory organizations controlled by the builders who fight any and everything that might add cost to the build.
>>
>>>
>>>
>
>More likely the reason the rebar corroded (if that was indeed the cause)
>was the close proximity to the ocean. Salt is extremely corrosive to
>unprotected steel as anyone in the northern states or Canada can attest
>with road salting ruining bridges and overpasses...
>
>You really have to connect climate change to everything, don't you -
>everything is a climate tragedy!
>
>I suspect the building failed due to plain old fashioned human stupidity.
>
>Didn't these people do a periodic engineering structural analysis -
>sometimes called a Depreciation Report? Oh, this is Florida...perhaps
>they don't like government interfering very much with good ol'
>enterprising folks?
>
>Read this (if you can - requires a subscription):
>
>https://www.academia.edu/7759895/The_Maintenance_of_Residential_Towers_in_Condominium_Tenure_A_Comparative_Analysis_of_Two_Extremes_Israel_and_Florida
>
>Florida's condominium bylaws:
>
>http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=0700-0799/0718/0718.html
>
>John

I wonder if the new Condo just south of the building destabilized the
ground.
The Goggle map satellite photos show the building is a recent
addition.

Cheers

On 6/26/2021 10:47 AM, Fred Bloggs wrote:
> On Saturday, June 26, 2021 at 9:38:32 AM UTC-4, Clive Arthur wrote:
>> On 25/06/2021 17:23, Fred Bloggs wrote:
>>
>> <snipped>
>>>
>>> That big reinforcing shear wall disintegrated like it was made out of sand.
>>>
>> I wonder about the aggregate. There are cases where pyrites in the
>> aggregate cause concrete to crumble and rebar to corrode. In the UK
>> it's particularly prevalent in Cornwall where tin mine tailings were
>> sometimes used in the aggregate on concrete block houses, they call it
>> 'Mundic'.
>>
>> You can buy a cheap house in Cornwall if it's made from Mundic Block and
>> you have cash - you won't get a mortgage. There are similar issues in
>> the West of Ireland.
>
> Good point. Aggregate and water contamination is a huge issue. The state of Connecticut is still dealing with a huge pyrrhotite contamination issue. The state set up a special agency using an insurance model to deal with paying for the time consuming and expensive repairs.
> https://www.fema.gov/case-study/connecticuts-crumbling-concrete
>
> In Florida seawater and salt contamination of concrete components a is major issue. They have gone so far as to develop a saltwater concrete which eliminates the problem. They have to use fiber reinforced rebar in this case, nothing else will do. The Ley video about the fiber rebar is total hysteria, they can do things like double the diameter of fiber rebar to get around that strain limitation and big cracks.
> https://www.wlrn.org/news/2017-08-31/university-of-miami-researchers-present-the-worlds-most-interesting-concrete-and-rebar
> And the sate already has several bridge, walkway and road projects using this material.
> http://seacon.um-sml.com/
> Salt contamination of aggregate and water used in the Champlain Towers construction most certainly could have accelerated its demise. The major inspection was due 20 years ago. This a real can of worms for the coastal cities in the state because you're looking at many billions of lost real estate value. People in Surfside area are already scared to death to remain in their seaside condos. I know some materials scientist or engineer saw this coming decades ago. But the development and profit fanatics would not be stopped.

In some of the post-collapse photos it looks like there are rusty re-bar
stains visible on the concrete, but when the building was intact looks
like they would've been concealed by drop-ceiling of the units or
covered up by the drywall:

<https://static01.nyt.com/images/2021/06/25/us/25miami-building-collapse-briefing-morning-summary3/25miami-building-collapse-briefing-morning-summary3-videoSixteenByNine1050-v2.jpg>