CHICAGO | St. Regis Chicago (Vista) | 1,191 FT | 101 FLOORS

[BVictor1]

Originally Posted by intrepidDesign

So I'm curious, it looks like floor plates of the hotel portion are being poured separately from the residential portions, hence the difference in progress. Is the plan to "tie" the two floor plates together at floor 13, where the hotel stops and the residences begin? If you look at the floor plans of the residences (again 13 and up) the eastern most core is only a stairwell, no elevators. I always knew the hotel would be physically walled off from the residences, but i just assumed the floor would be poured all at once. Can any shed any light on this process/decision?

Residential floors are above the hotel. We've got a ways to go for that.

[intrepidDesign]

Originally Posted by BVictor1

Residential floors are above the hotel. We've got a ways to go for that.

Right, well I guess what I'm really asking is; why are there separate floor plates at all? What's the reason for not pouring the entire floor all at once like other buildings?

[BVictor1]

Originally Posted by intrepidDesign

Right, well I guess what I'm really asking is; why are there separate floor plates at all? What's the reason for not pouring the entire floor all at once like other buildings?

Don't know, but they'll still be tied together via rebar.

[KOgc]

I think you may have a better chance at good consolidation of concrete when you use the bucket and drop method in the columns. Tough to fit the vibrator in the formwork with all of the rebar in there. The weight of the concrete when you drop it has enough pressure to consolidate well.

[harryc]

Originally Posted by KOgc

I think you may have a better chance at good consolidation of concrete when you use the bucket and drop method in the columns. Tough to fit the vibrator in the formwork with all of the rebar in there. The weight of the concrete when you drop it has enough pressure to consolidate well.

Thank you for the insight - it now seems common sense.

[Bombardier]

Originally Posted by intrepidDesign

Right, well I guess what I'm really asking is; why are there separate floor plates at all? What's the reason for not pouring the entire floor all at once like other buildings?

There would be too much to pour and finish in one day if they tried to do it all in one pour. The floor plate is just too large.

[nergie]

In today's Chicago Tribune there is an article about the Vista landing a record $700mil construction load from Ang Ping Bank in China.

[rlw777]

Originally Posted by jc5680

Looks like they are pouring the first slab above Wacker today…

Does anyone know why they use the buckets to drop concrete where the columns are and then fill in everywhere else with the pump? Is it a different mix?

(image from the webcam)

I saw a similar question on here before and happened to find this

The placement of fresh concrete on a horizontal surface can affect the
joint. Common practice has been to provide a bedding layer of mortar, of
the same proportions as that in the concrete, prior to placement of new concrete
above the joint. The ACI Manual of Concrete Inspection (ACI Committee
311 1981) recommends using a bedding layer of concrete with somewhat more
cement, sand, and water than the design mix for the structure.

from Joint Design for Reinforced Concrete Buildings pg 8

[the urban politician]

Originally Posted by nergie

In today's Chicago Tribune there is an article about the Vista landing a record $700mil construction load from Ang Ping Bank in China.

If there is a cause for nanners, this little bit of news should be it.

No Spire 2.0

Chicago is finally getting its next supertall, at long last.

[nergie]

http://http://www.chicagotribune.com...16-column.html

[maru2501]

going to be a great addition

[BVictor1]

Originally Posted by nergie

http://http://www.chicagotribune.com...16-column.html

And from Crain's...

http://www.chicagobusiness.com/reale...oreUserAgent=1

[cmmcnam2]

In Chicago, Ping An is an investor in Miami developer Crescent Heights' planned One Grant Park residential tower along the southern end of Grant Park. Ping An has committed more than $100 million of equity to the project, Chicago-based Crescent Heights Vice President Jason Buchberg said.

I thought this line stood out. Nice to see deep pocketed foreigners believing in the city and the skyline.

[marothisu]

Not like Dalian Wanda needed a loan to fund this thing at all, but I guess good to see(?).

[nergie]

http://i.imgur.com/etgWtDo.jpg[/IMG]

[nergie]

[kayosthery]

Originally Posted by chief56

Columns/shear walls most likely have higher concrete psi strength than the floor plates, hence the buckets at the column locations.

We seemed to have moved on to the construction loan thing...

However, this was the correct answer. Columns and shear walls are a higher strength mix. The slab mix usually has chemicals added that make it easier to pump, as well as either accelerator or retarder, depending on the time of year/temperature. The column and shear wall mixes are scheduled intermittently throughout the pour and placed via crane and bucket. This guarantees that the correct mix is being placed in the desired location. Pumping the higher strength mix would be crap shoot on whether you're getting the correct mix, or enough of it, in the spot you need it.

Now back to your regularly scheduled elation over a construction loan...

[the urban politician]

^ Not getting the attitude here.

We love the construction pics and knowledge, but how the hell does it all happen without the money to keep things going?

And construction financing for a project this huge is far from a sure thing. Hence, I think it's a major thing to celebrate.

[City Wide]

Originally Posted by kayosthery

We seemed to have moved on to the construction loan thing...

However, this was the correct answer. Columns and shear walls are a higher strength mix. The slab mix usually has chemicals added that make it easier to pump, as well as either accelerator or retarder, depending on the time of year/temperature. The column and shear wall mixes are scheduled intermittently throughout the pour and placed via crane and bucket. This guarantees that the correct mix is being placed in the desired location. Pumping the higher strength mix would be crap shoot on whether you're getting the correct mix, or enough of it, in the spot you need it.

Now back to your regularly scheduled elation over a construction loan...

Although nothing happens without them, my interest in construction loans is near zero.

But this reader is always interested in learning more about the actual construction process, so thanks for the explanation about concrete placement. Are you saying that the proper mix for the columns can't be pumped, even if done at a separate time from the slabs? I don't know why being forced through a 6" hose would change the mix of what's in the concrete.

[kayosthery]

Originally Posted by City Wide

Although nothing happens without them, my interest in construction loans is need zero.

But this reader is always interested in learning more about the actual construction process, so thanks for the explanation about concrete placement. Are you saying that the proper mix for the columns can't be pumped, even if done at a separate time from the slabs? I don't know why being forced through a 6" hose would change the mix of what's in the concrete.

It can be pumped, but may require different additives to do so, namely Super Plasticizer "Super P", to make it fluid enough. If the contractor is pouring a lot of the vertical work at one time, it will usually pump the concrete. Every time you place concrete with a pump though you have to order enough to lose in the pipe that runs from the stationary pump on Lower Lower Wacker all the way to the tip of the pump. All of that unplaced concrete gets blown back through the pipe to a concrete truck when finished. So, you need to be placing enough that your production gained through pumping is offsetting the cost of the time to crane and bucket, as well as the lost concrete in the pipe. There's a lot of other considerations too, for example, the crane might be busy doing other things, and pumping is the only option.

To the last part of your comment... I wasn't saying pumping changes the mix. I meant that you cannot be sure when the mix you want reaches the end of the placing boom and when the truck delivering that mix runs out. Not saying it can't be done, but it's a lot easier and faster to crane and bucket the vertical mix.