[CUclimber]

Forgive me if this question has been asked and/or answered here already.

It seems that with many of the super-tall buildings that are going up these days that a big challenge in their construction is pumping concrete hundreds of meters up to the highest floor under construction. Given the weight and density of concrete and the massive pumps that are required to do this, it's obvious as to why it's a difficult task.

The recent announcement of Nakheel's mega-tall 1,000m building in Dubai has raised this question for me: Why not construct a concrete mixing plant halfway up the building and mix it there? Once the structure gets up towards the upper limits of the ground-based pumps (500m or so?) why not just bring the dry concrete and water up the building and mix it on site? Is there a reason why the concrete has to be mixed off-site and pumped as a liquid from the ground?

[Coldrsx]

staging and weight distribution would be immediate concerns.

[natelox]

http://www.canyonranchmiamibeach.com/shared/images/updates/update06.jpg
http://www.canyonranchmiamibeach.com/shared/images/updates/update06.jpg

[Kelvin]

I think if you are going to bring the raw materials up by crane only to mix them at a higher elevation, then little would be gained as compared to bringing up the mixed product bucket by bucket. Perhaps the only real gain is the cycle time on the crane & bucket.

Mixing and batching is actually a fairly involved process - all the components need to be weighted precisely, water added judiciously, admixtures, etc. Finally - what if you had a bad batch? How do dispose of it 1500' up in the air? The other aspect is disassembling a batch plant and moving it up to its new position and reassembling it. Believe it or not there would be some fairly heavy pieces involved.

I could see somebody rigging up a vertical bucket hoist system that would permit a continuous stream of buckets to come up and return to the ground without requiring cycle time on the crane(s).

[Rilestone75]

Forgive me if this question has been asked and/or answered here already.

It seems that with many of the super-tall buildings that are going up these days that a big challenge in their construction is pumping concrete hundreds of meters up to the highest floor under construction. Given the weight and density of concrete and the massive pumps that are required to do this, it's obvious as to why it's a difficult task.

The recent announcement of Nakheel's mega-tall 1,000m building in Dubai has raised this question for me: Why not construct a concrete mixing plant halfway up the building and mix it there? Once the structure gets up towards the upper limits of the ground-based pumps (500m or so?) why not just bring the dry concrete and water up the building and mix it on site? Is there a reason why the concrete has to be mixed off-site and pumped as a liquid from the ground?

If going with this logic, you could also set up a smaller pumping station at 500M and have the base pump feed directly into that. Saves you from staging at 500M and is faster than hauling wet slopp up by the bucket with a crane that is probably already being used to lift other items.