Miami Beach, Champlain Towers South apartment building collapse, Part 16 24

[dik]

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Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[FJBnomics]

. I was following a thought process based on the article Maud posted for now. Please feel free to add any additional thoughts about the grade level drawing water based on the idea.

Sorry I jumped on the ceiling fan air flow drying train of thought on the ceiling of garage.

The fan drying the inside surface of garage walls, seems also to accelerate effects on walls too based upon your and Maud’s post, especially at upper portion of wall.

 

[zebraso]

no need to apologize. You can jump to that. The sources I read talk about drying cycle, but not necessarily about continuous water supply and continuous drying. So I'm trying to figure out how it is different. The capillarity thing makes me wonder how failed the membrane actually had to be. We see photos of cores, but did we ever see a photo of the membrane exposed?

 

[IanCA]

but did we ever see a photo of the membrane exposed

According to the Moribato report Link page S2A-1.1 the parking deck had no waterproofing.

 

[IanCA]

Saltwater rising from underground

Thanks very much for sharing Maud. That ties in with the annular voids caused by sulfates, as mentioned in the article posted by dik, facilitating capillary action, and also from Link page 8 which states "Evans and Taylor also noted that sea salt particles cause corrosion at a lower RH [relative Humidity] than NaCl [Sodium Chloride] particles, due to the fact that sea salt contains very hygroscopic magnesium salts" attracting moisture.

 

[IanCA]

Interesting for sure! It's fun to hear about other people's work.

Agreed, most of that is way out of my league, but I do know to keep my fingers at a safe distance when testing GM tubes powered from a 9V battery...

 

[IanCA]

In THIS building, there are three hot wires and one neutral. Across any two hot wires is 208V single phase.

I'm glad you guys are familiar with three-phase systems because the associated vector math will come in useful when we get on to talking about vibrations.

 

[zebraso]

the parking deck had no waterproofing.

It is interesting. The stampcrete fractures look pretty good. I hate to call that "curious", but.....

 

[Nukeman948]

entertainment

Thanks for the entertainment. Out of my comfort bubble but thought provoking.

associated vector math

Sorry Victor, I don't do vectors. I got a phone app for that maths stuff.

[sub]Garbage in, garbage out.[/sub]​

 

[FJBnomics]

It is interesting. The stampcrete fractures look pretty good. I hate to call that "curious", but.....

According to the Moribato report Link page S2A-1.1 the parking deck had no waterproofing.

I think the way the stampcrete has come up in sheets demonstrates how it was not bonded to structural deck below and trapping moisture between stampcrete and non waterproofed structural deck. I also feel the way some of the stampcrete is shifted at columns and the major concrete failure cracks in parking deck area near south wall and patio deck junctions, definitely point to the parking deck failure being due to chemical reactions in that area could be a huge factor in that area being initial failure point, near south wall. Couple that with construction vibrations next door, and cyclic loading of parking deck from auto movements and that area is a very stressed area.

I will be first to admit, my chemistry education ended as freshmeat in College, and had long been forgotten except for times where it affects everyday life like the voltaic cell battery in my autos. I remember as a kid my dad storing a 12V auto battery on a concrete pad outside our home and how it ate the paste in the concrete at a rapid rate and left honeycomb of aggregate and voids showing. From that time on, dad burned in my brain to put a wood board under auto battery to protect concrete. He was mechanical engineer so not chemistry major. Concrete patio was under a cover so not a lot of rain getting to it, but perhaps some in blowing rains.

Interesting short read on "Case Studies Show Galvanic CP Effective on Corroded Reinforced Concrete Structures". Interesting to note that repaired areas create a potential difference between old and new areas and basically cause the cancer to spread to new areas around repaired area. Here is quote below form short article:

"Chloride-induced corrosion of reinforcing steel in concrete is a major problem worldwide. Chlorides can be introduced into concrete through deicing chemicals, seawater, soil, or as contaminants in the concrete mix. This can lead to pitting corrosion and concrete deterioration."

"Localized repairs are often performed to address concrete corrosion damage. When a repair is completed, new corrosion sites can form just outside the repaired area and are driven by the residual chloride contamination and the difference in potential between the steel in the chloride- contaminated and chloride-free sections. When incipient anodes form, further repairs will be required. The patch repair process may be repeated several times over the remaining life of the structure."

https://blogs.ampp.org/case-studies...ve-on-corroded-reinforced-concrete-structures

 

[FJBnomics]

Per the link below, it clearly appears we have sulphate attacks where concrete or layers of concrete turned into powered mass. As stated earlier only lab tests of many samples of concrete will conclusively determine if more than one chemical process was going on at the same time, perhaps in different locations or layers.

"Types of chemical attacks on concrete structures per link"

"Following are the different chemical actions on concrete structures
Sulphate attack
Chloride attack
Alkali aggregate reaction
Carbonation
Acid attack"

"Magnesium sulphate also reacts with hydrated calcium silicate and makes concrete into powdered mass." "Concrete with low water cement ratio is less affected by magnesium sulphate while high water cement ratio concrete is highly affected. Sulphate-resisting Portland cement should be used where sulphates are present in the soil, water or atmosphere and come into contact with the concrete."

https://theconstructor.org/concrete/chemical-attacks-types-concrete-structures/7237/

 

[zebraso]

trapping moisture between stampcrete and non waterproofed structural deck.

Substitute membrane for stampcrete now. It's unfortunate when water proofing ends up sealing in moisture. I requires a lot more thought then what often gets put into it. And these so-called repairs are merely superficial attempts at stop gaps. Good post there.

Edit: since you mentioned vibrations next door...what if that cracked the non-structure supporting deck just beyond the membrane and that became the primary entry point for water? just throwing spaghetti. Is this where we have to do vector math?

 

[FJBnomics]

Edit: since you mentioned vibrations next door...what if that cracked the non-structure supporting deck just beyond the membrane and that became the primary entry point for water? just throwing spaghetti. Is this where we have to do vector math?

I am thinking the after construction aftermarket membrane stopped at pool deck side of planters between parking deck and pool deck. Planters create sag, so water is drained towards planters and ponds there making that already overloaded K-Line even more vulnerable with decaying reinforced concrete, probably construction joint in that area too. Then add vibrations to loosen things up even more, and Shazam!

How is that for some meatballs to go with your spaghetti? I assume vector math has to do with diagonal parking slab failure across a rebar grid, and motion vectors on columns from the vibrator next door?

Personally I am up for linear vector math, but not non-linear equations.

 

[IanCA]

"Types of chemical attacks on concrete structures per link"

Another great document, thank you very much.

 

[zebraso]

I assume vector math has to do with diagonal parking slab failure

I don't know. IanCa mentioned in reference to vibrations. One of the things that is missing in terms of another type of timeline is when and how severe the water entry was. Supposedly there was a mention by a worker that pumps were burning out running 24/7 to keep up. When was that? Were they pumping out a sump? When did it first become necessary to put up drip panels and where were they needed first? Who did it? were they approved by someone? Someone know these answers.

Edit: one might assume the pumping was from the drainage wells (not proper term), but would one king tide be accountable for burning out pumps? Too many questions. I can't imagine water from grade is what that was about. I mean at the point where Ostroff made the walk-through analysis I don't know if he was considering the drainage wells. But the question stands was that water on the floor of the garage or not. I still say there are people associated with the building that know these things. And I assume they have been questioned.

 

[IanCA]

since you mentioned vibrations next door...what if that cracked the non-structure supporting deck just beyond the membrane and that became the primary entry point for water?

I think there is a chance that if the structural deck was already weakened it could crack, or the cracking could be accelerated, between the deck side of the planter and stampcrete. I expect the stress could be concentrated there, where the step changes in stiffness occur.

 

[IanCA]

I assume vector math has to do with diagonal parking slab failure across a rebar grid, and motion vectors on columns from the vibrator next door?

I was thinking about the stated NV5 threshold of 0.5 inches per second, because if you have three measurements of say .558 longitudinal, .408 transverse, and .583 vertical, at close to the same frequency, I think you end up with a significantly higher resultant vector that's not aligned with any of the measurements axis. Is that right?

I got a phone app for that maths stuff.

Please can you check, assuming they are at the same frequency and in phase?

 

[AusTony2046]

Ahem,

If the three components are aligned in phase and each is 1 unit, the resultant will be sq root (3) units, ie 1.732 units.

 

[zebraso]

structural deck

Yes of course. Sorry. any distinction there that I may have been trying to insert does not have merit. And whatever I was trying to say should have been stated differently to convey what I meant. That way it could be determined if it had merit. There is no need to rehash that. I never had a bone about it.

 

[IanCA]

@zebraso I hope my clarification didn't come across as a criticism. It wasn't intended as such. I was only attempting to clarify for others reading at a later date. I appreciate you confirming that we are on the same page.

 

[zebraso]

I think you end up with a significantly higher resultant vector that's not aligned with any of the measurements axis. Is that right?

I don't have the answer, but I have another question. If these vibrations were felt throughout the structure, is it reasonable that they were not being damped? Are we talking about sheet pile still? Is that what they felt? Or was it impulse from an excavator banging around? Are you talking about reflections adding in a way that excites some local node. Is NV5 peak, rms, average? And is that the threshold for all damage? I should look it up.