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Higher and faster

by Stephen White on Aug 14, 2011

Lessons learned from Burj Khalifa will be vital in the construction of the Kingdom Tower.
Lessons learned from Burj Khalifa will be vital in the construction of the Kingdom Tower.

RELATED ARTICLES: French spiderman up for challenge of Kingdom Tower | Engineer: Kingdom Tower is practical challenge | Experts: tapered form of Kingdom Tower is ideal

RELATED ARTICLES: French spiderman up for challenge of Kingdom TowerEngineer: Kingdom Tower is practical challengeExperts: tapered form of Kingdom Tower is ideal

The Kingdom Tower may overtake the Burj Khalifa as the world's tallest building but it will lean heavily on its technology to do so.

Architects AS+GG’s declaration that the design of the Kingdom Tower will be twice as high as the Taipai 101 in Taiwan raises the bar yet again for both the design and the construction of super tall structures.

Add on the fact that it has to be finished within five years – the same time it took to put up the Burj Khalifa – it is safe to say building a tower beyond 1km is going to test the very limits of what is possible for man and machine.

Fortunately, according to the people tasked with working out how it will be built, the good news is the wheel does not need to be re-invented this time – although it may have to turn a lot faster.

As ever, building high means starting at the very bottom and the Kingdom Tower is set to be one of the deepest ever attempted. Buried in the flood of press releases and news stories released last week was the announcement that the tender process for the foundation work was already underway.

Those that have been following the project closely say that the foundations were one of the major factors in determining the building’s final height.

Some have speculated that plans for a mile-high version of the tower were abandoned after the soil of the Kingdom City location failed to take the massive pilings required after a series of tests earlier this year.

Instead it is likely that the 60m deep, 7,500m2 foundation will be based on the Burj Khalifa’s – a scaled-up high density, low permeability concrete mat designed to hold back the corrosive effects of salt water from the Red Sea.

Indeed, it seems the more the plans for Kingdom Tower solidify, the more likely that Burj Khalifa will be used as a blueprint. In the years to come, Dubai’s landmark will serve as useful reference point, which did not exist seven years ago. With the tender out, companies are working on the technicalities of meeting the five-year schedule.

“We are already working on it,” confirms Jens Bawidamann of Putzmeister, the company that poured the foundation and pumped concrete to an elevation of 606m for Burj Khalifa. Like many others, Putzmeister will be hoping that its experience on that project will hold it in good stead.

Cameron Bellman of BASF (the company that developed its admixture, the appropriately titled Glenium SKY) for Burj Khalifa, explains that his company would not need major breakthroughs to cope with the heat and height.

“The DNA would be the same and the concrete technology exists to deliver the high strength needed. Certainly a Putzmeister or Schwing could cope with the pumping,” he says. “But much will depend upon the raw materials locally available to the ready-mix producer.”

If the plans demand going beyond the limitations of the ready-mix and pumps, he points out that the Burj Khalifa could again provide a solution: “I know Samsung considered using a platform at 400m for secondary pumping. But due to the mix rheology this was not required and the concrete was pumped the 606m through one line at the base of the tower.”

Ironically one of the major hurdles will be building the infrastructure required to support the project, says one of the contractors on the Burj Khalifa.

“The major problem we aced during the construction was the logistics. The higher you go, the more problems you face,” says Philippe Dessoy, general manager at Besix.

Even in an oil-rich state like Saudi Arabia the realities of constructing a sustainable building in a cash-strapped world also have to be taken into consideration.

“I don’t know (when work will be begin).It will be interesting to see, everything that is happening in the news at the moment could have an effect,” says Bawidamann alluding to the reports of financial distress in the global markets.

According to Andy Smith of Hyder Consulting, it is the prickly issue of ROI that is the limitation of building at such height: “The thing to do is build it in a series of sub-problems and it becomes possible. The question is how patient is a developer and how quickly can we turn a building around.

“The materials to build twice as high as the Burj Khalifa exist: they’re not even at the cutting edge. The secret is to choose pieces of the puzzle you can reliably deliver and put them together.”