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Old August 7th, 2012, 07:00 PM   #3061
marcatio
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The large air compressor that was used during tendon installation was lifted from its longtime home in the corner by the perimeter wall and set on the bench above. It will be moved off site, as the excavator at street level is awaiting the return of the flatbed truck. Trash skips were loaded aboard the flatbed truck earlier for removal.
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Old August 7th, 2012, 08:26 PM   #3062
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It's interesting to see that the number and position of the tendons are different on every pad. From this you can see that the perimeter columns on the corners will face the most upward pressure when the tower is completed. And that the designers take into account that the forces that will pull and push on the tower foundations will be different on all 4 corners.

It's fantastic that with the webcams we can see such small things that are very important for the foundation that we usually don't see.


Momo1435,

You are absolutely correct in your observations. Foundations of this type for such a tall structure must not only support the gravity loads from above, but must also resist uplift from wind loads, plus siesmic loads as well. And you are correct concerning the number of tendons in the different footings. And as you mention, the webcam is quite instructive, and one can gain an insight into how a building like this is constructed. Keep your eyes open and take in the details.
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Old August 7th, 2012, 08:30 PM   #3063
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And now, the flatbed truck has arrived. The excavator is ready to load the large air compressor. It will be leaving the site. The small mini-excavators continue filling the void in the core footing. Forms that were used are being stockpiled for later removal.
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Old August 7th, 2012, 08:50 PM   #3064
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Because the compressor is large, it is leaving being towed by a dump truck. The flatbed truck waits by the job site gate, probably waiting to receive the forms.
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Old August 7th, 2012, 10:38 PM   #3065
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Quote:
Originally Posted by marcatio View Post
And now, as I write, the final tendon is being installed. The dirt has come from the various excavations that took place on site while hammering and digging rock for footings, which is mainly rock dust. They may run the excavator back and forth, using its tracks for compaction before placing the waterproofing membrane. Since it rests on the bedrock, there is no settling.

Please, anyone else that has additional info, please chime in!!
What does the waterproofing membrane do? It protects the footings from underground water?
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Old August 7th, 2012, 11:50 PM   #3066
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Or the underground floors
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Old August 8th, 2012, 03:28 PM   #3067
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On the job today:

This morning, concrete was poured for the footing along the 56th Street perimeter wall. In the space vacated by the large air compressor yesterday, the rebar crew is now located, with rebar bending table and rebar. They were previously located where the new footing poured this morning is now located. Parging (the black coating that is painted onto the concrete, which is a water barrier) is being applied to the west walls whose forms were stripped yesterday. A load of lumber was delivered, seen near the south footing pads, presumably to be used for forming those footings. Workers are working within the core void that was backfilled yesterday, and also placing plywood ( presumably for forms) around the rebar protruding from the core footing.
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Old August 8th, 2012, 04:45 PM   #3068
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Quote:
Originally Posted by marcatio View Post
On the job today:

This morning, concrete was poured for the footing along the 56th Street perimeter wall. In the space vacated by the large air compressor yesterday, the rebar crew is now located, with rebar bending table and rebar. They were previously located where the new footing poured this morning is now located. Parging (the black coating that is painted onto the concrete, which is a water barrier) is being applied to the west walls whose forms were stripped yesterday. A load of lumber was delivered, seen near the south footing pads, presumably to be used for forming those footings. Workers are working within the core void that was backfilled yesterday, and also placing plywood ( presumably for forms) around the rebar protruding from the core footing.
Thanks for the fantastic update.

Question: why do they need to put black paint to waterproof the concrete? Isn't concrete already waterproof? And why isn't the black paint everywhere then? Why only on some sections?
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Old August 8th, 2012, 05:30 PM   #3069
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The black paint (parging) is applied to those surfaces that are directly against earth/rock. Interior walls would not recieve this treatment. Moisture can migrate through the concrete.

From the American Society of Civil Engineers:

"Moisture that travels through concrete floor slabs can damage floor coverings such as carpet, hardwood, or vinyl. To determine the severity of the problem, the moisture dome test can be used to obtain the vapor flow rate. For most floor coverings, the vapor flow rate should be less than 1.4 kg/day (3 lb/day). A moisture barrier and open-graded gravel are used to prevent both water vapor and capillary rise through concrete floor slabs. The main structural and construction details to prevent moisture migration through basement walls are a drainage system at the base of the wall to prevent the buildup of hydrostatic water pressure and a waterproofing system applied to the exterior wall surface. The key to minimizing moisture migration through flat slab ceilings is to provide drainage of the flat slab surface, seal the joints, and prevent the cutting of holes through the flat slab ceiling."
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Old August 8th, 2012, 06:20 PM   #3070
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Four small pads within the core footing are currently being filled with concrete. The forms for these were previously assembled on the backfilled area, and lined with waterproofing membrane. The concrete is being placed from the street via one excavator transferring concrete from one concrete bucket to another bucket being delivered to the forms by the triple-boom Hitachi. The southwest corner of the site has been cleared of debris. Rebar is visible on the far west wall, where the worker on the manlift is currently working. Formwork construction continues on the south footing pads.

Last edited by marcatio; August 8th, 2012 at 06:43 PM. Reason: addition to post
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Old August 8th, 2012, 07:16 PM   #3071
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Quote:
Originally Posted by marcatio View Post
The black paint (parging) is applied to those surfaces that are directly against earth/rock. Interior walls would not recieve this treatment. Moisture can migrate through the concrete.

From the American Society of Civil Engineers:

"Moisture that travels through concrete floor slabs can damage floor coverings such as carpet, hardwood, or vinyl. To determine the severity of the problem, the moisture dome test can be used to obtain the vapor flow rate. For most floor coverings, the vapor flow rate should be less than 1.4 kg/day (3 lb/day). A moisture barrier and open-graded gravel are used to prevent both water vapor and capillary rise through concrete floor slabs. The main structural and construction details to prevent moisture migration through basement walls are a drainage system at the base of the wall to prevent the buildup of hydrostatic water pressure and a waterproofing system applied to the exterior wall surface. The key to minimizing moisture migration through flat slab ceilings is to provide drainage of the flat slab surface, seal the joints, and prevent the cutting of holes through the flat slab ceiling."
Thanks so much. You are a very welcome addition to this website. You are single handedly making this one of the best threads (THE best thread IMHO) on this site. Thanks a million.
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Old August 8th, 2012, 07:52 PM   #3072
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Hope you folks aren't tired of my updates!! Must be "dignitary day". On the Park Avenue webcam, there's a line of people against the guard rail just inside the jobsite gate watching the action and progress. Don't you wish you were there??
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Old August 8th, 2012, 08:38 PM   #3073
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We'll never get tired of your updates, as 600West said, you made this thread the best thread on the forum. I plan on studying structural engineering and your insights are very helpful to me

Btw, one question, how do they protect the tendons from water/moisture? Are they made outta stainless steel or do they have a waterproof layer too?
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Old August 8th, 2012, 09:04 PM   #3074
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Hey guys, speaking of the webcams, did anyone catch me waving to one of the cameras yesterday? I was on my bike on the corner looking inside.
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Old August 8th, 2012, 09:06 PM   #3075
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Great updates, this afternoon you can really see the main core wall rebar going in...also very cool... you now can see the footings being formed for the four passenger elevators within the core.
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Old August 8th, 2012, 09:38 PM   #3076
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Thanks to you all. I enjoy bringing the updates. The problem is, that this webcam is way too entertaining for me. This to me is way better than reality TV!! Many can argue about the architectural merits (or de-merits depending on your view), but for me, ever since I was a child, seeing tall buildings go up has always been a thrill.

Let me share a diorama that I have built. This currently resides in my basement.



Here's a detail of the floor deck on my diorama to be poured:



Kanto, Good luck and best wishes on your wish to study structural engineering.
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Old August 8th, 2012, 09:47 PM   #3077
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Totally awesome diagram.

BTW, once they start putting up a lot more concrete forms if you can explain that and show pictures of exactly how they put together the forms for all the different shapes they have to pour that will be awesome. I've always wondered how they do it - it would seem to be quite complicated to me. But maybe they have some cool tricks and equipment to make it easier.

This cam could get me fired from my job :-)
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Old August 8th, 2012, 10:20 PM   #3078
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Quick update:

As we near the end of yet another workday at 432 Park Avenue, several items have been accomplished. A quick summary: Today, backfilling around the core, and the west wall took place after waterproofing was installed. Four small pads were formed and poured within the core. On the four small pads within the core, small box outs have been placed. Forms placed around core reinforcing. Underslab piping started.
All this in preparation for future slab on grade casting.

Concrete was placed in a footing by 56th Street this morning. If I am not mistaken, rebar (most likely corner reinforcing between the far west perimeter wall and a future wall to be cast??) was visible on the perimeter wall. I beleive that the reinforcing was placed while the perimeter wall was cast previously, then the concrete covering the bent bars was ground off ( the manlift has been seen with a worker grinding concrete),then straightened. South footings are being formed.
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Old August 8th, 2012, 10:24 PM   #3079
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Nice to see that I'm not the only one who likes models. I have built a Willis Tower and a Twin Towers 2 complex from lego, however your models are far superior to mine. I wish I could build such models
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Old August 8th, 2012, 10:32 PM   #3080
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One last item I forgot: an area (along the 56th Street perimeter wall) just to the south of the five south footings being formed has been outlined in red paint. This could indicate the location of a major footing to be placed, possibly for the base section of the climbing tower crane. However, this could just be speculation, but it would seem to be a likely location. Time will tell.
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